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SP 34 (1987) : Handbook on Concrete Reinforcement and
Detailing [CED 2: Cement and Concrete]

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BUREAU OF INDIAN STANDARDS

HANDBOOK

€X>NCREIE REINFORCEMENT

AND DETAILING

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN. 9 BAHADUR SHAH ZAFAR MARG

NEW DELHi110002

SP 34 : 1987

FIRST PUBLISHED AUGUST 1 987
FIRST REPRINT DECEMBER 1992
SECOND REPRINT NOVEMBER 1995
THIRD REPRINT DECEMBER 1996
FOURTH REPRINT JULY 1997
FIFTH REPRINT MARCH 1999

UDC 666.982.24(021)
ISBN 81-7061-006-0

PRICE Rs.600.00

PRINTED IN INDIA

AT NUTAN PRINTERS, F-89/12, OKHLA INDUSTRIAL AREA, PHASE-I, NEW DELHM10020

AND PUBLISHED BY

BUREAU OF INDIAN STANDARDS, NEW DELHMIO 002

FOREWORD

Users of various civil engineering codes have been feeling the need for explanatory
handbooks and other compilations based on Indian Standards. The need has been
further emphasized in view of the publication pi the National Building Code of India in
1970 and its implementation. The Expert Group set up in 1972 by the Department of
Science and Technology, Government of India carried out in-depth studies in various
areas of civil engineering and construction practices. During the preparation of the Fifth
Five-Year Plan in 1975, the Group was assigned the task of producing a Science and
Technology plan for research, development and extension work in the sector of housing
and construction technology. One of the items of this plan was the production of design
handbooks, explanatory handbooks and design aids based on the National Building
Code and various Indian Standards and other activities in the promotion of the National
Building Code. The Expert Group gave high priority to this item and on the
recommendation of the Department of Science and Technology, the Planning
Commission approved the following two projects which were assigned to the Bureau of
Indian Standards :

a) Development programme on code implementation for building and civil
engineering construction, and

b) Typification for industrial buildings.

A Special Committee for Implementation of Science and Technology Projects (SCIP)
consisting of experts connected with different aspects was set up in 1974 to advise the BIS
Directorate General in identification and for guiding the development of the work. Under
the first programme, the Committee has So far identified subjects for several explanatory
handbooks/compilations covering appropriate Indian Standards codes specifications
which include the following :

Design Aids for Reinforced Concrete to IS : 456-1978 (SP : 16-1980)

Explanatory Handbook on Masonry Code (SP: 20-1981)

Explanatory Handbook
on Codes of Earthquake Engineering (IS : 1893-1975 and
IS : 4326-1976) (SP : 22-1982)

Handbook on Concrete Mixes (SP: 23-1982)

Explanatory Handbook on Indian Standard Code of Practice for Plain and Reinforced
Concrete (IS : 456-1978) (SP : 24-1983)

Handbook on Causes and Prevention of Cracks in Buildings (SP : 25-1984)

Summaries of Indian Standards for Building Materials (SP : 21-1983)

Functional Requirements of Industrial Buildings (Lighting and Ventilation)
(SP : 32-1986)

Timber Engineering (SP : 33-1986)

Water Supply and Drainage with Special Emphasis on Plumbing (SP : 35-1987)

Functional Requirements of Buildings*

Foundation of Buildings

Steel Code (IS : 800-1984)

Building Construction Practices

Bulk Storage Structures in Steel

Formwork

Fire Safety

Construction Safety Practices

Tall Buildings
Loading Code

This Handbook provides information on properties of reinforcing steel and detailing
requirements, including storage, fabrication, assembly, welding and placing of reinforce-
ment in accordance with IS : 456-1978. As a result of the introduction of limit state
method of design for reinforced concrete structures and the concept of development
length, detailing has become extremely important as many of the design requirements are
to be* nriet through detailing. This Handbook is expected to guide the designer in detailing
which include correct positioning of bar*^ for a particular type of structural element and
preparation of bar bending schedule. The detailing requirements as specified in IS : 456-
1978 have been brought out as applicable to different structural elements in a building
and explained, wherever necessary. The relevant Indian Standards and other literature
available on the subject have been taken into consideration in preparing the Handbook.
The Handbook will be useful to concrete design engineers, field engineers and students of
civil engineering.

Some of the important points to be kept in view in the use of the Handbook are :

a) The reinforcement has to cater to forces (bending moment, shear force, direct
compression or direct tension) at sections consistant with development length re-
quirements at the particular section. Sound engineering judgement shall be exerci-
zed while applying the provisions herein and detailing should be such that the struc-
tural element satisfies the requirements of performance for which it is meant.
Typical detailing drawings are included to illustrate one possible method of
arrangement of bars for a particular condition. They should not be construde as the
only possible method.

b) Considering the importance of ductility requirements in structures subjected to
severe earthquakes, a separate section is included on the detailing requirements for
buildmgs in severe earthquake zones (Zones IV and V of IS: 1893-1984).

c) International Standard ISO 4066-1977 'Buildings and civil engineering drawings-
Bar scheduling' is reproduced in Appendix B as a supplement to what is contained
m the Handbook.

d) The Handbook does not form part of any Indian Standard on the suhjeci and does
not have the status of an Indian Standard. In case of dispute about interpretation
or opinion expressed in the Handbook, the provisions of relevant Indian Standards
only shall apply. The provisions of the Handbook particularly those relatim^ tc
other literature should be considered as only supplementary iniornwtinn

e) The Handbook is expected to serve as a companion document to the three hand-
books already published on the subject of reinforced concrete, namely, SP : 16-1980,
SP : 23-1982 and SP : 24-1983.

All dimensions are in mm unless otherwise specified.

The Handbook is based on the first draft prepared by the Central Public Works
Dcpart-ment, New Delhi. Shri B. R. Narayanappa, Deputy Director, and Shri P. S.
Chadha, Officer on Special Duty, Bureau of Indian Standards (BIS), were associated
with the work. The assistance rendered by Shri A. C. Gupta, Assistant Chief Design
Engineer, National Thermal Power Corporation (NTPC), New Delhi, in the preparation
of this Handbook specially in the formulation of drawings is acknowledged.

The draft Handbook was circulated for review to National Council for Cement and
Building Mat;erials, New Delhi; Structural Engineering Research Centre, Madras; Indian
Institute of Technology, Madras; Indian Institute of Technology, New Delhi; Andhra
Pradesh Engineering Research Laboratories, Hyderabad; Engineering Construction
Corporation Ltd, Madras; Enginecr-in-Chiefs Branch, Army Headquarters, New Delhi;
Engineering Consultants (India) Limited, New Delhi; Gammon India Ltd, Bombay;
M/sC. R. Narayana Rao, Architects & Engineers. Madras; STUP Consultants Ltd,
Bombay; Research, Design and Standards Organization, Ministry of Railways,
Lucknow; Irrigation Department, Government of Gujarat; M/s H. K. Sen and
Associates, Calcutta; Siddharth Shankar and Associates (Consulting Engineers), New
Delhi; Roy and Partners (Architects & Engineers), New Delhi; Shrish Malpani
(Architects & Engineers), New Delhi; and the views received were taken into
consideration while finalizing the Handbook.

(iv)

CONTENTS

Page

Section 1 Steel for reinforcemcnl 1

Section 2 Detailing functions 9

Section 3 Structural drawing for detailing 13

Section 4 General detailing requirements 27

Section 5 Bar bending schedule (including do's and dont's in

detailing) 53

Section 6 Foundations 67

Section 7 Columns 83

Section 8 Beams 97

Section 9 Floor slabs 119

Section 10 Stairs 143

Section 1 1 Special structures— deep beams, walls, shells and

folded plates, water tanks, RC hinges, concrete pipes,

machine foundations, and shear walls 153

Section 12 Ductility requirements of earthquake resistant

building 187

Section 13 Transport, storage, fabrication, assembly and

placing of steel reinforcement 193

Section 14 Typical structural drawings 205

Appendix A Welding 209

Appendix B ISO 4066-1977 Building and civil engineering

drawings — bar scheduling 221

Appendix C Dimensions and properties of hard-drawn steel wire

fabric and other bars 227

SECTION 1
Steel for Reinforcement

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34<S&TH987

SECTION 1
STEEL FOR REINFORCEMENT

1.0 Reinforcing bars/ wires for concrete
reinforcement shall he any of the following
conforming to accepted standards:

a) Mild steel and medium tensile steel bars
[IS: 432 (Part I)- 1982 Specification for
mild steel and medium tensile steel bars and
hard-drawn steel wire for concrete rein-
forcement : Part 1 Mild steel and medium
tensile steel bars {third revision)].

b) High strength deformed steel bars/ wires
[IS : 1 786- 1 985 Specification for high
strength deformed steel bars and
wires for concrete reinforcement
(ihird revision).

c) Hard-drawn steel wire fabric [IS : 1566-1982
Specification for hard-drawn steel wire
fabric for concrete reinforcement (second
revision)].

The requirements for manufacture and supply
of different types of steel reinforcement are briefly
highlighted in 1.1 to 13.43.

Note ~ Different types of reinforcing bars« such as plain
tors and deformed bars of various grades, say Fe415
(N/mm^) and Fe500 (N/rnm^). should not be used side by
tide as this practice will lead to confusion and error at site.
However* secondary reinforcement such as ties and stirrups,
may be of mild steel throughout even though the main steel
may be of high strength deformed bars.

1.1 Mild Steel and Medium Tensile Steel Bars

Kl.l Reinforcement supplied shall be classi-
fied into the following types:

a) mild steel bars, and

b) medium tensile steel bars.

1.1*1.1 Mild steel bars shall be supplied in
ihe following two grades:

a) mild steel bafs. Grade 1; and

b) mild steel bars« Grade II.

Note — In all cases where the design seismic coefficient
[see IS : 1893-1984 Criteria for earthquake resistant design
of structures {fourth revision)] chosen for the structure is 0T)5
or more (which include earthquake zOnes tV and V) and for
structures subjected to dynamic loading, use of
Grade II bars is not recommended.

1 .1 .2 Physical/ Mechanical Properties — The
requirements for physical/ mechanical properties
of mild steel and medium tensile steel bars are
given in Table t.l.

1.1.3 Tokrance — l\it rolling and cutting
tolerances shall be as specified in 1.1.3.1 and
1.13.2.

1.1.3.1 Bars in straight lengths

a) The tolerance on diameter shall be as follows:

Diameter Tolerance,

-A . percent

Over Up to and

including

25
35
50
80
100

mm
25
35
50
80

100

mm
±0.5
±0.6
±0.8
±1.0
±13
±1,6

b) The permissible ovality measured as the
difference between the maximum and mini-
mum diameter shall be 75 percent of the
tolerance (±) specified on diameter.

c) The tolerance on weight per m length shall
be as follows:

Diameter

Tolerance,
percent

' Over

Up to and ^
including

—

±7

±5

±3

1.1.3.2 Coiled bars

a) The tolerance on diameter shall be ±0.5 mm
for diameters up to and including 12 mm.

b) The difference between the maximum and
minimum diameter at any cross-section shall
not exceed 6.65 mti^.

Note — No weight tolerance is specified for coiled bars.

1.2 High Strengtii Deformed Steel Ban

1.2.1 Deformed steel bars/ wires for use as
reinforcement in concrete shall be in the following
three grades:

a) Fe4l5,

b) Fe500, and

c) Fe550.

HANDBOOK ON CONCRETE REINFORCEMENT AND OETAIUNG

TABLE I.I REQUIREMENTS FOR REINFORCING BARS

(Clauses 1.1.4. 1.2.2, 1. 2.5 and 1.3.1}

IS No.

Type of
Reinforcement

(2)

Nominal Size
OF Baks

<3)
(mm)

IS: 432 (Pirt I)- MiM steel (Grade 1} S.M J 0.12,16.20
1982*

22,25,28.32.36,
40,45,50

Mikl steel (Grade II) 5.6.8,10,12,16.20

22,25,28.32,36.
40.45.50

Medium tensile steel 5,6,8,10,12,16

20,22,25,28,32
36,40,45.50

Characteristic Minimum Ultimate

Strength Tensile Stress

(Yield Stress or
2 Percent Proof''
Stress)

(4)
(N/mm3)

250
240

225
215
350

340
330

}
}
}

(5)
(N/mm2)

410

370

540

510

Composition

OF Steel

Conforming

TO IS

(6)
IS : 226-l975t

Fe 410.0 of
IS : 1977-1975$

Fe 540 W-HT of
IS : 96l-1975§

Minimum Elonc*
ation on gu/^ge
Lkngtii of
5.65N/AiEA

(7)

(percent)

IS: 1786-198511

High strength
deformed bars/

4,5,6.7,8.10,12,16.
18.20,22.25,28,32,
36,40,45,50

415

(for Fe 415)

500

(for Fe 500)

to percent more than
the actual 0.2
percent proof stress
but not less than
485.0 N/mm^

C -0.30
S -0.06
P - 0.06
S + P-O.ll

percent more than C - 0.3

the actual 0.2 S -0.055

percent proof stress P — 0.055

but not Jess than S + P - 0.105
545.0 N/mm'

14.5

12.0

S
S

S
pj

2
H

>
2

2
ft

IS No.

(I)

Type of

RElNrORCEMENT

(2)

Nominal Size
OF Bars

(3)
(mm)

tS : 1566-198111

Hard-drawn steel
wire fibric

(See Note t)

Characteristic

Strength

(Yield Stress or

2 Percent Proof

Stress)

(4)
(N/mm2)

SSO

(for Fe 550)

480

Minimum Ultimate
Tensile Stress

<5>
(N/mm2)

6 percent more than
the actual 0.2

Eeroent proof stress
ut not less than
585 N/mm^

570

Composition

OF Steel

Conforming

to is

(6)

C -0.3
S - 0.055
P - 0.050
S + P-O.IO

Minimum Elong-
ation ON GUAGE
Length of
5.65v/XREr

(7)
(percent)

8.0

— 0.05
-0.05

7.5

(over a sa

length of ,f

Note 1 —The mesh sizes and sizes of wire for square as well as oblong welded wire fabric commonly manufactured in the country are given in
Appendix C *

Note 2 — The weight and area of differem sizes of bars are given in Appendix C.

Note 3 — Generally avaikble ex stock:

Mild steel bars— ^,^10, ^12, ^16. ^, ^5, <^2

Deformed sled bwi-#8« »10. #12, #16, #20, #22. #25, #28, #32

The maximum length of reinforcing bars available ex stock is 13 m.

Note 4 — For each bundle/coil of bars/ wires, a tag shall be attached indicating cast No./ lot No., grade and size by the manufacturer or the supplier.

^Spedfication for mild steel and medium tensile steel bars and hard-drawn steel wire for concrete reinforcement: Part I Mild steel and medium tensile sted
ban (thini nvi^on).

tSpedfication for stiuctural steel (sundard quality) Cflfth revision).
iSpecirication for stnietural steel (ordinary ciuatity) (second revision).
jSpeaficatton for structural steel (high quality) {second revision).

#Specification for high strength deformed steel bars and wires for concrete reinforcement (third revision).
HSpedfication for haid-dnwn steel wire fabric for concrete reinforcement (second revision).

i
IS

SP : 34(S&T>-1987

Note — The figures following the symbol Fc indicates the
ftpeciried mtnimum 0.2 percent proof stress or yield stress in
N/mm*.

1.2.3 Tolerance

1.2.3.1 • Cutting tolerance on length — The
cutting tolerances on length shall be as specified
below:

a) When the specified length is +75 mm
not stated to be either a -25 mm
maximum or a minimum

b) When the minimum length is +50 mm
specified - mm

Note — These are tolerances for manufacture and supply
and are not applicable for fabrication. For allowable toler-
ances for bending and cutting during fabrication see
Section 13.

1.2.3.2 Mass — For the purpose of checking
the nominal mass, the density of steel shall be
taken as 0.785 kg/cm^ of the cross-sectional area
per metre run. Toleraifces on nominal mass shall
be as follows:

Nominal Size
mm

Tolerance on the Nominal Mass,
Percent when Checked in

Up to and
including 10

over 10 up to
and includ-
ing 16

Over 16

Batch

(each

Specimen

not less

than
0.5 m)

±7

±5

Indivi-
dual
Sample
(not less

than
0.5 m)

-8

±3

Indivi-
dual

Sample
for

Coils*

±8
±6

±4

1.2.4 Physical I Mechanical Properties — The
requirement for physical/ mechanical properties of
high strength deformed steel bars are given in
Table 1.1.

Note 1 - the nominal diameter or size of a deformed
bar/ wire is equivalent diameter or size of a plain round
bar/ wire having the same mass per metre length as the
deformed bar/ wire.

Note 2 — The effective diameter, 0, of a deformed
bar/ wire is determined as follows, using a bar/ wire not less
than 0.5 m in length:

where

/162.13 w

w - mass in kg weighed to a precision of ±0.5 percent, and
L - length in m measured to a precision of ±0.5 percent.

1.3 Hard-drawn Steel Wire Fabric

1.3.1 General— Hard-drawn steel wire fabric
consists of longitudinal and transverse wires (at
right angles to one another) joined by resistance
spot welding. Fabrication of wire fabric by
welding has the quality of factory fabrication and
reduces cost of labour and fabrication in the field.

1.3.2 rvpe5 — Hard-drawn steel wire fabric
shall be made in the following two types:

a) square mesh, and

b) oblong mesh.

The diameter of wires in the square mesh varies
from 3 to 10 mm; the diameter being same inr both
longitudinal and transverse directions. In this case
both longitudinal and transverse bars may serve
as main reinforcement. The diameter of wire in
the oblong mesh varies from 5 to 8 mm in the
longitudinal direction and 4.2 to 6 mm in the
transverse direction. The wires in the direction of
larger diameter can serve as main reinforcement
and the wires in the cross direction can serve as
distribution steel.

1.3.2.1 The maximum width of wire fabric
in rolls is 3.5 m; the length of this type of fabric is
limited by the weight of rolls which may range
from 100 to 500 kg. The maximum width of fabric
in the form of sheets is 2.5 m and the maximum
length is 9.0 m. The dimension of width is to be
taken as centre-to-centre distance between outside
longitudinal wires. The width of wires fabric in
rolls or sheets shall be such as to fit in with the
modular size of 10 cm module and length in
suitable intervals (see Fig. (1.1).

l.IA Rolls
1111

^ s: ; :

B <^ ^

' 1

t M "

•For coils, batch tolerance is not applicable. At least 2
samples of minimum one metre length shall be taken from
each end of the coil.

MB Sheets

Fig. I.l Welded Wire Fabric

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

1,3.2.2 The fabric may be designated for
ordering purposes by the number of the standard
and the reference number given as in the first
column of Table C-J of Appendix C, or
alternately a complete description of the fabric
may be given.

When denoting the size of rolls or sheets of
oblong mesh fabric, the first dimension shall be
the length of the main wires.

Example : Hard -drawn steel wire fabric according
to IS : 1566 corresponding to SI No. 5 : 50 sheets
of size 5 m X 2 m

1.3.3 Mass — The nominal mass of fabric
shall be calculated on the basis that steel weighs
0.785 kg/cm^ of nominal cross-sectional area per
metre run.

1 .3.4 Tolerances

1.3.4.1 Tolerance on size of mesh — The
number of spaces between the external wires in a
sheet or roll shall be determined by the nominal
pitch. The centre-to-centre distance between two
adjacent wires shall not vary by more than 7.5
percent from the nominal pitch. The maximum
variation in the size of any mesh shall be not more
than 5 percent over or under the specified size,
and the average mesh size shall be such that the

total number of meshes contained in a sheet or
roll is not less than that determined by the
nominal pitch.

1.3.4.2 Tolerance on size of sheet — when
fabric is required to be cut to specified
dimensions, the tolerance shall be as follows:

a) for dimensions of
5 m and under

b) For dimensions
over 5 m

25 mm under or over
the specified
dimensions

'/^ percent under or
over the specified
dimension.

NoTt — These are tolerances for manufacture and supply
and are not applicable for fabrication.

1.3.4.3 Tolerance on weight of fabric — The
tolerance on the weight of fabric shall be as
follows:

a) When the specified weight
is not stated to be either a
maximum or a minimum

b) When the specified weight
is stated to be maximum

6 percent

- 12 percent

c) When the specified weight — 12 percent
is stated to be a minimum -0

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 2
Detailing Functions

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T).1987

SECTION 2
DETAILING FUNCTIONS

2.1 General — In preparing drawings and
bending schedules, the following factors shall be
kept in view:

a) The engineer's design and the design
requirements;

b) The cutting and bending of the rein-
forcement;

c) The placing and wiring in position of rein-
forcement;

d) The maintaining of the position of rein-
forcement;

e) The preassembly of cages;
Concreting;

g) The accommodation of other trades and
services;

h) The measurement of quantities; and

j) Economy in the use of steel.

2.2 Design — The following requirements of the
designer shall be borne in mind:

a) The quantity, location and cover of steel
reinforcement should be simply, correctly
and clearly shown.

b) The placing drawings and bending schedules
should be adequately cross-referenced, easily
read and capable of easy checking in the
drawing office and on site.

c) It should be possible to locate a detail
readily, should a doubt arise.

d) One detailer should be able to take over
from another with a minimum of delay and
direction.

e) Detailing should be done in such a way that
secondary streses caused by support con-
ditions, shrinkage, temperature variations,
bursting ef&cts of laps and splices, and
stress concentrations arising froni hooks
and bends are counteracted.

2.3 Cutting and Bending — Prepare bending
schedules on standard size sheets small enough to
facilitate handling by clerical, fabrication and
placing personnel.

Standardize cutting lengths and ensure that
bending details are simple and easy to read. So
compile the schedules that delivery of the required
reinforcement for each component can be effected
without the need for abstracting from schedules.

The system of bar-referencing should be coherent
and systematic, and should lend itself to easy
identification and to use in computer systems, if
necessary.

2.4 Placing and Wiring in Position — Ensure
that drawings are simple, pictorially clear, and
adequately detailed to enable the fixer to place
bars exactly where required. Avoid crowding
drawings with information by detailing by
components and also if necessary by preparing
separate details for bottom and top steel in slabs.
Ensure that reinforcing steel that connects
elements to be cast at different times is so detailed
that it is included with the portion to be cast first,
for example, splice bars for columns, continuity
reinforcing for beams and slabs to be cast in
portions. If the order of casting is not clear, detail
splices in one of the sections with suitable cross-
references. Where the complexity of the detail is
such that an out of the ordinary sequence is
required to place the reinforcement, ensure that
such sequence is shown on the detail.

2.5 Maintaining Position of Reinforcement —

Reinforcement that has been placed and wired in
position should not be displaced before or during
the concreting operation. Ensure that bar
supports and cover blocks are so scheduled or
specified as to maintain correct bottom and side
cover and that high chairs and stools are detailed
to support upper reinforcement mats at the
correct level.

2.6 Preassembly of Cages and Mats — Where

required, so detail the reinforcement to
components such as columns, foundations,
beams, and walls that it can be conveniently
preassembled before being placed in position.
Ensure that assembled units are sturdy enough to
stand up to handling and erection, and that they
are not so heavy that they cannot be lifted by the
men or equipment available for the work.

2.7 Concreting Ensure that the reinforcement
can be so spaced as to allow placing and efficient
consolidation of the concrete.

2.8 Other Trades and Services Take note of
the positions of down pipes (especially inlets and
outlets), sleeves, pipes, and electrical conduits,
whether shown on the structural layout or not. To
avoid site difficulties, show them on the
reinforcement details where necessary.

2.9 Measurement of Quantities - It is

important that the quantity surveyor and the
contractor should be able to compute the mass of

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIMN(.

SP : 34iS&T)-l987

steel used at any stage in a contract. Bending
schedules prepared as recommended in 2.3 will
assist in meeting this requirement. Ensure that
placing drawings and bending schedules are
adequately cross-referenced and that all revisions
are suitably recorded. If. in the case of a levision,
there is any possibility of doubt, prepare separate
schedules showing only the revision, with
adequate cross-referencing.

2.10 Economy in Use of Steel — The type of
steel used is generally specified by the designer but

bear in mind that up to one-third of the mass of
steel can be saved by using high tensile steel
instead of miid steel. The saving can be
considerable as the difference of cost between the
rates for mild steel and high tensile steel placed in
position is relatively small. Furthermore, as the
rates for smajl diameters are higher than those for
large diameters, it is desirable to use the largest
available size of bar within the design
requirements. Larger bars also produce stiffer
cages and are not easily displaced.

HANDBOOK ON CONC RKTK RKINKORCKMENT AND DKTAIMNG

SECTION 3
Structural Drawing for Detailing

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

SECTION 3
STRUCTURAL DRAWING FOR DETAILING

3.1 Size of Drawing — The structural drawing
for a large project should generally be of one size,
for convenience both in the drawing office and on
the site. The preferred sizes of drawing sheets are
given in Table 3.1.

detailer/ designer and no general recommenda-
tions can be given in this respect. Some
commonly used scales are given below as
examples:

TABLE 3.1 DRAWING SHEET SIZES

Untrimmed

No.

Designation

Trimmed Size

Size (Min)

(»)

(2)

(3)

(4)

mm X mm

841 X 1189

880 X 1230

ii)

594 X 841

625 X 880

iii)

420 X 594

450 X 625

iv)

297 X 420

330 X 450

210 X 297

240 X 330

vi)

148 X 210

165 X 240

3.1.1 The dimensions recommended for all
margins and the divisions of drawing sheets into
zones are given in Fig. 3.1 (A to F).

3.1.1,1 The title block is an important
feature ih a drawing and should be placed at the
bottom right-hand corner of the sheet, where it is
readily seen when the prints are folded in the
prescribed manner. The size of the title block
recommended is 185 X 65 mm.

3.1.2 Separate sheets should be used for each
type of structural member or unit so that a floor
slab would be detailed on one sheet, beams on
another, and columns on a further sheet, etc.
Alternatively, for small jobs each standard size
sheet could be used to detail one floor of the
structure so that the ground floor slab, beams and
columns could be detailed on one sheet and the
first floor members on another.

3.1.3 Layout — ThQTQ cannot be a single
standard layout for the detailing of reinforced
concrete drawings. .However, it is the usual
practice to draw th&(key) plan in the upper left
hand corner of the fheet, with the elevations and
details below and on to the right side of the plan.
Schedules and bending details are placed in the
upper right corner of the drawing. Figure 3.2
gives a broad outline of layout recommended. In
large projects, the bending schedule can be
omitted from individual drawings and a separate
bending schedule drawing may be prepared.

3.2 Scale of Drawing — Scales shall be so
chosen as to bring out the details clearly and to
keep the drawings within workable size. The
choice of scale will depend at the discretion of the

Plan
Elevation.

1 : 100, I : 50
1:5, I : 30

Sections — 1 : 50, I ; 30, I : 25, I : 20, 1 : 15,
1 : 10

3.3 Information to be Shown on Structural
Drawings

3.3.1 The overall sizes of the concrete
members shall include the sizes of any necessary
chamfers and fillets at corners. Also, the exact
position, shape, size and spacing of the
reinforcement within concrete members, as well as
the required dimensions of the concrete cover to
the reinforcement shall be given.

3.3.2 The position of any holes required in the
members for service pipes and details of any pipes
or other fixings to be cast-in with the concrete,
and also, the position and details of construction
joints and special recesses, etc, shall be indicated.

3.3.3 When foundations or ground floor slabs
are detailed, information regarding the underside
conditions shall be shown, such as the use of
waterproof paper, the thickness of blinding (the
lean layer of concrete), if required.

3.3.4 Notes should be used freely on detailed
drawings. The most important being the *bar
marks* which give information about each, or a
series of similar reinforcing bars. The notes
should be concise and precise, and shall not be
ambiguous. The notes which apply to the whole
drawings, such as the specifications of the
concrete to be used, size of chamfers and fillets,
and concrete cover, etc, can be placed under a
general heading at the bottom or side of the
drawing.

3.3.5 The beams, wall slabs, floor slabs and
columns, etc, the main dimensions of the
structure, such as the distances between columns,
heights between floors, beam and column sizes,
and floor and wall thicknesses, etc, as calculated
by the design engineer shall also be shown on the
drawings.

Sections shall be drawn to atleast twice the
scale of plans or elevations to which they refer,
while complicated joints such as may occur at the
intersections of columns and beams may be
detailed to larger scale, say 1 : 4.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

tf>

««» i U 'I « I 13 I 11' I 10 I 9 I e I 7 I 6 I' 5 I 4 I 3 I 2 I

^^U.

o
o

o
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o
z
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z

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Z

It » * I M I tt I ri I l< I tf I * I . I < I t I

M * I j

UNTRIMMED

TITLE BLOCK

FOLDING

MARK

TRIMMED

MARGIN

FOLDING MARK

All dimensions in millimetres.
3.IA AO SHEET LAYOUT

SP : 34(S&T)-I987

|S.5.

U-

""■

hf+n

tf>

1 1

« 1

11 1 i6 1 'i 1 •

7 1 6 Is 1 4

1 1 1 2 1 1

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TITLE BLOCK

12 !

11 1 10 1 9 [ e

1 7 1 6 1 5 1 4

1 tv I

/margin

\trimmed ^

Ss^FOLDING MARK

N^UNTRIMMED

All dimensions in miilimetrcs.
3. IB AI SHEET LAYOUT

5 5

8|7|SISItl9l2l 1

» I « I »

TITLE BLOCK

F OLDING
MARK

TRIMMED

UNTRIMMED

MARGIN

"V ^ FOLDING MARK

All dimensions in niilimetres.
3.IC A2 SHEET LAYOUT

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

-5

CUT SIZE

UNCUT SIZE

TITLE 6LOCK

5 rS

-CUT SIZE-
UNCUT SIZE

TITLE ALOCK

3. ID A3 SlZt

3. IE A4 SIZE

-CUT size-

UNCUT SIZE-

TITLE BLOCK

•-5

DIVISION OF ZONES

SHEET SIZE

DIVISION

No. OF

ZONING

NO
ZONING

€

3. IF A5 SIZE

3.IG DIVISION OF ZONES

All dimensions in millimetres.

Fig. 3.1 Margins and Division of Zones for Different Drawing Sheets

HANDBOOK ON ( ON( RKTK REINFORC KMKNT AND DFTAII IN(;

SP : 34(S&T)-1987

- -1

FRAMING PLAN

SECTIONAL
DETAILS

KEY PLAN

OR
SCHEDULE

AND
BENDING
DETAILS

SECTIONAL DETAILS

NOTES

TITLE BLOCK

1 1

Fig. 3.2 Typical Layout of a Drawing

3.3.6 Structural drawings prepared by the
designer shall show details of reintorcement and
all other information needed for detailing the
reinforcement. The drawings shall also indicate,
by separate notes, live loads, concrete strength,
quality and grade of steel, number of bars to be
lapped and lengths of the laps, and if necessary
special instructions regarding erection of
formwork, fabrication and placing of steel.

3.3.7 It is convenient to detail the
reinforcement by units which generally consist of
footings, walls, columns, each floor and roof. A
separate structural drawing supplemented by bar
bending schedule should preferably be made for
each unit. For small structures, the entire
requirements may be handled as one unit. For a
large project a particular unit such as floor may
be divided to correspond with the construction
schedule.

3.3.8 To ensure that all the reinforcement is
properly placed or positioned in a unit,
longitudinal section or cross-section should be
shown in addition to plan and elevation of the
unit on which the bars are shown.

3.3.9 The drawing should be complete and
clear so as to leave no doubt on any point of
construction. Complete and accurate dimensions
shall be shown. Clear and adequate details for

special and unusual condition shall be given to
ensure proper placing of reinforcement. Details of
covers and intersections of walls, construction
joints, window and door openings, and similar
special features should be shown in the relevant
drawings alongwith sketches, if necessary.

3.3.10 For clear demarcation of reinforcement
bars, those in the near face shall be shown in full
lines and those that are placed in the far face shall
be shown in dotted lines.

3.3.11 All bars, straight or bent requiring
hooks bends, shall be properly designated by the
designer or a note to this effect included in the
drawing.

3.3.12 Lengths of laps, points of bend, cut-off
points and extension of bars should be specified
by the designer. The dimensions Z., 7, /. 5 and
L/4, etc, shown on typical drawings shall not be
used unless justified by structural analysis.

3.3.13 Wherever possible, ail control and
construction joints should be indicated on
structural drawings and constructional details
provided for such joints.

3.3.14 Notes ami Instructions Any
ambiguity and scope for misinterpretation of
instructions shall be avoided. All instructions
shall be in imperative form, specific, brief and
clear.

HANDBOOK ON CON< RKTK UKINKOH< KMilN T ANI> DKTAIMNt.

SP : 34(S&T)-1987

3.3.15 Schedules — The reinforcement details
of slabs, beams, columns and many other parts of
structures may be effectively shown on working
drawings in a tabular form, known as a schedule
(see Section 5).

3.4 Symbols and Abbreviations — Symbols and
abbreviations to be adopted in the drawings for
reinforced concrete construction are given in 3.4.1
to 3.5.6. All reinforcement bars used in the
structures shall be suitably designated and
numbered both on drawing and schedule.

3.4.1 Symbols Relating to Cross-Sectional
Shape and Size of Reinforcement

a) <f> plain round bar or diameter of plain
round bar;

W D plain square bar or side of plain square
bar; and

c) # deformed bar (including square twisted
bar) or nominal size (equivalent diameter
or side) of the deformed bar {see Note
under 3.4.5).

3.4.2 Symbols Relating to Shape of the Bar
along its Lengths

Alt .

Alternate bar

Bent bar

Bottom bar

Minimum

max

Maximum

Straight bar

Stp

Stirrup

Spiral

Column tie

Top bar

Non-

Alternativolv, all symbols rnJ

3.4.3 Symbols Relating to Position and
Direction

Limit of area covered by
bars

^ — ^ Direction in which bars

extend

i.4.4 Symbols Relating to Various Structural
Members

Bm or
Col

^^g

Sb or S

Beams

Column(s)

Footing(s)

Girders

Joints(s)

Lintel(s)

Lintel beam(s)

Slab(s)

Longitudmal wall

Cross wall

Centre line

(0)

Each way

Spacing centre-to-centre

NoTi-: - Alternatively, all symbols may be in capitals,

3.4.5 The symbols, abbreviations and notes
shall be used in a manner that will not create any
ambiguity. A few examples for representing
diameter, spacing, number of bars, etc, are
illustrated be!ow; ' -

a) # 20@ 200 means 20 mm diameter
detormed dars spacea at 200 mm centre-to-
centre.

h) 20-# 12 means 20 numbers of 12 mm
diameter deformed bars.

c> 032-St-l2 EW means 12 numbers of
32 mm diameter plain round straight bars m
each direction.

Note — The symbol relating to cross-sectional shape and
size — (^ or # is used on the left hand side of the
numerical value of the diameter to avoid confusion that it
may be interpreted as the number of times the diameter if
used on the right hand side of the numerical value cf the
diameter.

3.4.6 The use of the same type of line for the
same purpose considerably enhances the clarity
and usefulness of the drawing. The following
graphical symbols are suggested:

Symbol

Designation I Description
Concrete line (thin)

Unexposed concrete or masonry wall line (thin)

Reinforcement (thick)

Reinforcement in a different layer (thick).

Section of a reinforcing bar
Centre line

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

Svmboi

— M*

SP : 34(S&T)-I987

Designation/ Description

Dimension line

z=(t-~fl=

Concrete beam framing into column which
extends through floor

#r— ^:

Concrete beam framing into column which
stops at floor

-»

Bar shown bent at right angle to the paper

Bar with hooks

Bar with 90° bends

Bars shown separated on the drawmg

One sheet of welded fabric on plan

Identical sheets of welded fabric in a row
Level mark in elevation

Level mark in plan

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S& T)-I987

3.4.7 Additional drawing conventions for use drawings— Symbols for concrete reinforcement'
on drawings for reinforcement as suggested in is reproduced in Table 3.2.
ISO : 3766-1977 'Building and civil engineering

TABLE 3.2 DRAWING CONVENTIONS

No.

(I)

Convention
(2)

Symbol
(3)

i) Bends shall normally be drawn to scale

Bends with the smallest permitted bend radius may
be drawn with intersecting straight lines

ii) A bundle of bars may be drawn with a single line,
end markings indicating the number of bars in the
bundle

Example : Bundle with three identical bar?

iii) Each set of identical bars, stirrups or ties shall be
indicated by one bar. stirrup or tie drawn with
continuous extra-thick lines, with a continuous
thin across the set terminated by short oblique
lines to mark the extreme bars, stirrups or ties.

A circle drawn with a continuous thin line connects
the *set line' with the correct bar, stirrup or tie

iv) Bars placed in groups, each group spaced over the
same distance and containing an identical number of
identical bars

>r y I"'

-y—^

v) Two-way reinforcement shall be shown in section, or
marked with text or symbol in order to show the
direction of bars in the outside layer on each face
of the construction in plan or elevation

< >

vi) On plan drawing for simple arrangements, the top-layer
and bottom-layer reinforcement shall have letter
indicating the location of the layer added to the
symbols

( Continued)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

No.

(I)

TABLE 3,2 DRAWING CONVENTIONS {Contd.)

Convention
(2)

Symbol
(3)

If end marks are used, the end marks shall be
drawn upwards or to the left for the bottom-layer
and downwards or to the right for the toplayer

(fl— bottom r— top)

vii) On elevations of walls with reinforcement on both
faces, the reinforcement shall have letters added
to the symbols, indicating the location of the
layer

If end marks are used, the end marks shall be
drawn upwards or to the left for face reinforcement,
and downwards or to the right for near face
reinforcement.

(/VF— near face Ff— far face)

liL

FF,

k /

viii) If the arrangement of the reinforcement is not clearly
shown by the section, an additional sketch showing
the reinforcement may be drawn outside the
section.

ix) All the types of stirrups or ties present shall

be indicated on the drawing. If the arrangement is
complicated, it may be clarified by the aid of a
sketch in connection with the notation.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

3.5 Marks for Parts of Buildings

3.5.1 Marks are used to designate the different
structural members of a structure. Different
structural members of a structure shall be marJced
using symbols, abbreviations and notations
indicated in succeeding clauses and in the manner
indicated in other clauses.

3.5.2 A key framing plan shall be prepared to
a convenient scale and the t^o axes marked one
side with alphabets A, B, C, etc, and the other
with numbers {see Fig. 3.3). Normally with
rectangular pattern, the same key framing plan
may be used for all floors. However, if
arrangement of beams vary for different floors a
separate key framing plan with grid arrangement
and areas may be used for each of the floor. The
floors shall be specified in accordance with the
requirements of IS : 2332-1973 ^Specifications for
nomenclature of floors and storeys' and
abbreviations BT and MZ shall be used for
basement and mezzanine, respectively, for
example:

Basement

Mezzanine

Floor 1

Floor 2

3.5.3 Columns — Columns and foundations
shall be specified by grid arrangement giving
reference to the floor, for example {see Fig. 3.3 A).

FG Col El Footing for Column El

Col 2E1 Column El at floor 2

(that is, column for
storey 2, or column
between ^oor 2
and 3).

3.5.4 Beams, slabs and lintels, and tie beams
shall be consecutively numbered from left-hand
top corner {see Fig, 3.3A).

3.5.5 If longitudinal section of the beam is
shown, the grid of the column or number of the
column supporting the beam is being detailed
shall be as indicated as in fig. 3.3B and, if
possible, inset on the drawing showing the key
framing plan. On the other hand if a beam
schedule is included, a table [see Fig. 3.3C] may
be prepared and inset on the drawing showing the
key framing plan [see Fig. 3.3A].

3.5.5,1 beams or slabs that are similar may
be given in the same number.

3.5.6 Walls — Marking of walls shall be made
in the serial order starting from top left corner of
plan and proceeding towards the right, followed
by subsequent rows in order. Longitudinal walls
and cross-walls shall be marked separately {see
Fig. 3.4) and identified in the drawing with
reference to the serial number of the floor.

Example
2 WL —

4 WX -

1 Longitudinal wall No. 1
at floor 2 (between
floor 2 and 3).

3 Cross-wall No. 3 at
floor 4 (between floor 4
and 5).

I SCA6 TO K -SUNK LlSb > J 8m 27 WLJ B^ 3t "*,!!

3T/LB '>

3.3A.

Fig. 3.3 Typical Arrangement for the Key Framing Plan and Marking Different Structural

Members {Continued)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34<S&T)-I987

COL 2 E4

_ni_

ilf=^;i^=l

•100

COLI E, C0L1 E} con E) COLi E4

DETML OF Bm ( OCTAIL OF Btn 13 DETAH OF Bn, 20

AMO Bm 7 SMUAfl 4N0 Bm tA SIMILAR AND Bm ^ S«flLAIt

33B

St n

BeunNo.

Floor

Spanning Between

AtLevd

B.1

Ej Gi

+3300

B»14

c. c.

+3500

B.27

B,, B,,

+3500

B.28

C4 c,

+3500

B.28A
( Landing Beam )

B.29

G4 C,
B6 B„

+ 1750
+3500

Lb I

El Gi

+2440

Lb 9

A, A4

+2440

3.3r

Fig. 3.3 Typical Arrangement for the Key Framing Plan and Marking
. Different Structural Members

WL,

^L,

WX,

WX2

WX3

WL3

WL*

WL,

WX4

WXs

WX,

WX7

WL7

WL,

WLto

WX,

WX,o WX„

WL,,

WX,3

WL,2

WL,j

WX,2

WXu

wx„ WX„

WL,4

WL,5

WL„

Fig. 3.4 Typical Marking Details for Walls

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 4
General Detailing Requirements

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T).1987

SECTION 4
GENERAL DETAILING REQUIREMENTS

4.1 Cover — Reinforcement shall have concrete
cover (nominal) and the thickness of such cover
(exclusive of plaster or other decorative finish)
shall be as follows:

a) At each end of reinforcing bar not less than
25 mm, or twice the diameter of such bar
whichever is greater;

b) For a longitudinal reinforcing bar in a
column not less than 40 mm or the diameter
of such bar whichever is greater. In the case
of columns with a minimum dimension of
20 mm or under, whose reinforcing bars do
not exceed 12 mm, the cover may be reduced
to 25 mm;

c) For longitudinal reinforcing bar in a beam
not less than 25 mm or the diameter of such
bar, whichever is greater;

d) For tensile, compressive, shear or other
reinforcement in a slab not less than 15 mm
or the diameter of such reinforcement,
whichever is greater; and

e) For any other reinforcement not less than
15 mm or the diameter of such reinforce-
ment, whichever is greater.

Note — The values of cover suggested are nominal cover
as specified in the drawings. The cover shall in no case be
reduced by more than one-third of the specified cover or
5 mm whichever is less. During construction it is
essential to ensure that these tolerances are met.

4.1.1 Increased cover thickness may be
provided when the surfaces of concrete members
are exposed to the action of harmful chemicals (as
in the case of concrete in contact with earth
contaminated with such chemicals), acid, vapour,
saline atmosphere, sulphurous smoke (as in the
case of steam-operated railways), etc, and such
increase of cover may be between 15 and 50 mm
over the values given in 4.1 above as may be
specified by the Engineer-in-Charge. However, in
no case cover should exceed 75 mm.

4.1.2 For reimorced concrete members of
marine structures totally immersed in sea water,
the cover shall be 40 mm more than that specified
in 4.1, but total cover should not exceed 75 mm.

4.1.3 For reinforced concrete structures/
structural members, periodically immersed in sea
water or subject to sea spray, the cover of
concrete shall be 50 mm more than that specified
in 4.1, but total cover should not exceed 75 mm.

4.1.4 For concrete of grade M25 and above,
the additional thickness of cover specified in 4.1.!
to 4.1.3 may be reduced by half.

4.2 Development of Stress in Reinforcement

4.2.1 Development Length of Bars in Tension
or Compression — The calculated tension or
compression in any bar at any section shall be
developed on each side of the section by an
appropriate development length or end anchorage
or by a combination thereof.

Note — Development length is the embedded length of
reinforcement required to develop the desi^ itiength of the
reinforcement at a critical section. Critical sections for
development of reinforcement in flexural memben are at
points of maximum stress and at points within the span
where adjacent reinforcement terminates, or is bent.
Provisions of 4.6 J <c) should be satisfied at simple supports
and at points of inflection.

4.2.2 The development length U is given by:

4 Tbd

". •.'

-♦

fc . 1

. *■

'*it*-i-

B-»-T

where

4> - nominal diameter of the bar,

as = stress in bar at the section considered at
design load, and

Tbd = design bond stress for bars in tension
given in 4.2.2.1.

Note I — The development includes anchorage values of
hooks in tension reinforcement (see 4.3.1).

Note 2 — For bars of sections other than circular, the
development length should be sufficient to develop the

stress in the bar by bond.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I9«7

4.2.2 J Design bond stress in limit state
design method for plain bars in tension shall be as
fo^ows:

MIS M20 M25 M30 M35 M40

1.0 !,2 1.4 1.5 1.7 1.9

Grade of
concrclg

Design bond
stress
Tbd, N/mm^

For deformed bars, these values shall be increased
by 60 percent. For bars in compression, the values
of bond stresses for bars in tension shall be
increased by 25 percent.

4.3 Anchoring Reinforcing Bars— It is

important to note that when a bar is subjected to
both tension and compression, the anchorage
value should correspond to the one which gives
the maximum value^ and at the same time
individual requirements (with respect to tension
and compression) are also satisfied as specified in
4.3.1 to 4,3 J.

4.3.1 Anchoring Bars m Tension

4.3.1.1 Deformed bars may be anchored in
straight lengths (without end anchorages),
provided the development length requirements are

satisfied. Plain bars should ndr t>e normally
anchored through straight lengths alone and
should be provided with hooks.

4.3.1.2 Bends and hooks

a) Bends ~ The anchorage value of a standard
bend shall be taken as 4 times the diameter
of the bar for each 45*^ bend subject to a
maximum of 16 times the diameter of the
bar.

b) Hooks — The anchorage value of a standard
U-type hook shall be equal to 16 times the
diameter of the bar.

The anchorage values of standard hooks and
bends for different bar diameters are given in
Table 4.1.

4,3.2 Anchoring Bars in Compression — The
anchorage length of straight bar m compression
shall be equal to the development length of bars
in compression as specified in 4.2.2. The projected
length of hooks, bends and straight lengths
beyond bends, if provided for a bar in
compression, should be considered for
development length {see Fig. 4.1).

TABLE 4.

Bah Diameter, mm
Anchorage Value of Hook, cm

ANCHORAGE VALUE OF HOOKS AND BENDS

6 8 10 12 16 18 20 22 25 28 32 36

9.6 12.8 16.0 19,2 25.6 28.8 32.0 35.2 40.0 44.8 51.2 57.6

Anchorage Value of 90^* Bend, cm 4.8 6.2 8.0 9,6 12.8 14.4 16.0 17.6 20.0 22.4 25.6 28.8

4 • min

4-0 min

STANDARD HOOK

STANDARD 90^ BEND

STANDARD HOOK AND BEND
Type of Steel Minimum Value of k

Mild steel 2

Cold-worked steel 4

Note I — Table is applicable to all grades of Veinforcement bars.
Note 2 — Hooks and bends shall conform to the details given above.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T>-19«7

CRITICAL SECTION r-i

PROJECTED LENGTH ONi.Y
^ SHALL BE COflSJOEBED
♦• FOR THE PURPOSE OF i .

— C

Note — !n compression hooks and bends arc ineffective and cannot
be used as anchorage.

Fig, 4 I Development Length in Compression

4.3.3 The development length' values for fully
stressed bars in tension as well as compression
based on 4.2.2 are' given in Tables 4.2, 4.3 and 4,4.

Note ~ If the amount of steel provided at a design
section is more than that required from design
cdnsideration, the development length given in Tables 4.2,
4.3 and 4.4 may be nnodified as:

- _ ^» r e quired
" Au provided

Unless otherwise specified, JLj- modiried development length
should be used in detailing reinforcement.

43.4 Mechanical Devices for Anchorage —
Any mechanical or other device capable of

developing the strength of the bar without
damage to concrete may be used as anchorage
with the approval of the Engineer ~in-Charge.

4.3.5 Amhoring Shear Reinforcement

a) Inclined bars — Tht development length
shall be as for bars in tension; this length
shall be measured as under:

I) in lension zone, from the end of the slop-
ing or inclined portion of the bar {see
rig. 4.2 A), and

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T>-1987

2) In the compression zone, from the mid
depth of the beam (see Fig. 4.2B).

b) Stirrups and ties — Not withstanding, any
of the provisions of this Handbook, in case
of secondary reinforcement, such as stirrups
and transverse ties, complete development
length atid anchorage shall be deemed to
have been provided when the bar is bent
through an angle of at least 90^ round a bar
of at least its own diameter and is continued
beyond the end of the curve for a length of
at least eight diameters, or when the bar is

bent through an angle of 135*^ and is
continued beyond the end of the_cjurvc for a
length of at least six bar diameters or when
the bar is bent through an angle of 1 80^ and
is continued beyond the end of the curve for
a length of at least four bar diameters.

4.3.6 Special Members — Adequate end
anchorage shall be provided for tension
reinforcement in flexural members where
reinforcement stress is not directly proportional to
moment, such as sloped, stepped or tapered
footings, brackets, deep beams and. members in

TABLE 4.2 DEVELOPMENT LENGTH FOR FULLY STRESSED PLAIN BARS

/, = 250 N/mm' for bars up to 20 mm diameter

= 240 N/mm^ for bars over 20 mm diameter

(Tabulated values are in centimetres)

Bar

Tension

Bars for

Grade of

Concrete

Compression

Bars for

Grade of

Concrete

Diameter

>k.

' MIS

M20

M25

M30 ^

^ M15

M20

M25

M30 '

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

32.6

27.2

23.3

21,8

26.1

21.8

18.6

17.4

43.5

36.3

29.0

34.8

29.0

24.9

23.2

54-4

45.3

38.8

36,3

43.5

36.3

31.1

29.0

65.3

54.4

46.6

43.5

52.2

43.5

37.3

34.8

87.0

72.5

62.1

58.0

69.6

58.0

49.7

46.4

97.9

81.6

69.9

65.3

78.3

65.3

55.9

52.2

108.8

90.6

77.7

72.5

87.0

72.5

62.1

58.0

114.8

95.7

82.0

76.6

91.9

76.6

65.6

6i.2

130.5

t08.8

93.2

87.0

104.4

87.0

74.6

69.6

146.2

121.8

104.4

97.4

116.9

97.4

83.5

78.0

167.0

139.2

119.3

III.4

133.6

111.4

95.5

89.6

187.9

156.6

134.2

125.3

150.3

125.3

107.4

100.2

Note I ~ The development lengths given above are for a stress of 0.87 /, in the bar.

Note 2 — It is important to note that hooks should normally be provided for plain bars in tension. Therefore, the
straight length required in such cases is equal to the value taken from the table minus the anchorage value of hook.

TABLE 4.J DEVELOPMENT LENGTH FOR FULLY STRESSED DEFORMED BARS

/, = 415 N/mm'
(Tabulated values arc in centimetres)

Bar

Tension

Bars for

ADE of

Concrete

Compression

Bars for

Grade of

Concrete

Diameter

MIS

M20

M25

M30 '

' MI5

M20

M25

M30 ^

(1)
mm

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

33.8

28.2

24.2

22.6

27.1

22.6

19.3

18.1

45.1

37.6

32.2

30.1

36.1

30.1

25.8

24.1

56.4

47.0

40.3

37.6

45.1

37.6

32.2

30.1

67.7

56.4

48.4

45.1

54.2

45.1

38.7

36.1

90.3

75.2

64.5

60.2

72.2

60.2

51.6

48.1

101.5

84.6

72.5

67.7

81.2

67.7

58.0

54.2

112.8

94.0

80.6

75.2

90.3

75.2

64.5

60.2

124.1

103.4

88.7

82.7

99.3

82.7

70.9

66.2

141.0

117.5

100.7

94.0

112.8

94.0

80.6

75.2

158.0

I3I.6

112.8

105.3

126.4

105.3

90.3

84.2

180.5

150.4

128.9

120.3

144.4

120.3

103.2

96.3

203.1

169.3

145.0

135.4

162.5

135,4

116.1

108.3

Note The

development length:

s given above

are for a

stress of 0.87 /, in

the

bars.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAHJNG

SP : 34(S&T)-1W7

TABLE 4.4 DEVELOPMENT LENGTH FOR FULLY STRESSED DEFORMED BARS

/,=*500 N/mm*
(Tabulated values are in centimetres)

Bar

Tension

Bars for

Grade of

Concrete

Compression

Bars for

Grade of

Concrete

Diameter

MIS

M20

M25

M30 ^

^ MI5

M20

M25

M30 '

(I)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

40.8

34.0

29.1

27.2

32.6

27.2

23.3

21.8

54.4

45.3

38.8

36.3

43.5

36.3

31.1

29.0

68.0

56.6

48.5

45.3

54.4

45.3

38.8

36.3

81.6

68.0

58.3

54.4

65.3

54.4

46.6

43.5

108.8

90.6

77.7

72.5

87.0

72.5

62.1

58.0

122.3

102.0

87.4

81.6

97.9

81.6

69.9

65.3

135.9

113.3

97.1

90.6

108.8

90.6

7?.7

72.5

149.5

124.6

106.8

99.7

119.6

99.7

85.4

79.8

169.9

141.6

121.4

113.3

135.9

113.3

97,1

90.6

190,3

158.6

135.9

126.9

152.3

126.9

108.8

101.5

217.5

181.3

155.4

145.0

174.0

145.0

124.3

116.0

244.7

203.9

174.8

163. 1

195.8

163. 1

139.8

130.5

Note — The

development length

s given above

are for a

stress of 0.87 /, in the

bar.

THIS POINT IS TO BE
TREATED AS CUT-OFF
^ POINT FOR THE PURPOSE
OF DEVELOPMENT LENGT!
IN TENSION ZONE

^ L,

4.2A IN TENSION ZONE

THIS POINT IS TO BE
TREATED AS CUT-OFF
POINT FOR THE PURPOSE
OF DEVELOPMENT LENGTH
IN COMPRESSION ZONE

4.2B IN COMPRESSION ZONE

Fig. 4.2 Anchoring Inclined Bent-up Bars

lANU&OOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 54(S&T)-1987

which the tension reinforcement is not parallel to
the compression face.

4.4 Reinforcement Splicing — Splicing is
required to transfer force from one bar to
another. Methods of splicing include lapping {see
4.4.2). welding (see Appendix A) and mechanical
means (je^- 4.4.3).

4.4 J Where splices are provided for
continuity in the reinforcing bars (tension bars in
beams), they shall be as far as possible away from
the sections of maximum stress and be staggered.
It is recommended that spHce in flexural members
should not be at sections where the bending
moment is more tha.i 50 percent of the moment of
resistance of the section. Not more than half the
bars shall be spliced at a section.

Where more than one half of the bars are
splfced at a section or where splices are made at
points of maximum stress, special precautions
shall be taken, such as increasing the length of lap
and/ or using spirals or closely spaced stirrups
around the length of the splice.

Note I — The stirrups provided should be able to resist a
tension equal to the full tensile force in the lapped bars and
should be provided in the outer one-third of the lap length
at both ends with at least three stirrups on either side (see
Fig. 4.3). In case of thick bars (say <^ > 28 mm), lap splices
should be completely enclosed by transverse reinforcement,
for example, in the form of small compact stirrups or spirals
{see Hg. 4.4 (A and B)].

Note 2 ~ Careful detailing is necessary when
reinforcements are to be spliced. Therefore location and
details of splices should be determined at the design stage
itself and indicated in the drawing. Preferably splicing
details should not be left to be decided at the site of
construction.

4.4,2 Lap Splices

a) Diameter of bars for lap splicing — Lap
splices shall not be used for bars larger than
36 mm. For larger diameters, bars may be
welded (see Appendix A).

In cases where welding is not practicable,
lapping of bars larger than 36 tnm may be
permitted, in which case addftional spirals
should be provided around the lapped bars
{see Fig. 4.4A).

b) Staggering of Jap splices — Lap splices
shall be considered as staggered if the
centre-to-centre distance of the splices is not
less than 1.3 times the lap length (see Fig. 4.5)
calculated as given in (c) below. Bars
could be lapped vertically one above the
other or horizontally, depending upon the
space requirement.

c) Lap length in tension — Lap length includ-
ing anchorage value of hooks in flexural
tension shall be Z^ or 30 <^ whichever is
greater and for direct tension 2 Ld or 30
whichever is greater. The straight length
of the lap shall not be less than 15 <^ or
200 mm, whichever is greater {see Fig. 4.6).

where

Ld = development length

Note — splices in direct tension members shall be
enclosed in spirals made of bars not less than 6 mm in dia-
meter with pitch not more than 10 cm. Hooks/ bends shall
be provided at the end of bars in tension members [see
Fig. 4.4C).

d) Lap length in compression — The lap
length in compression shall be equal to the
development length in compression calcula-
ted as in 4.2.2 {see Tables 4.2, 4.3 and 4.4),
but not less than 24 <f).

e) Requirement of splice in a column — In
columns where longitudinal bars are offset
at a splice, the slope of the inclined portion
of the bar with the axis of the column shall
not exceed I in 6, and the portions of the

>150

Fig. 4.3 Transverse Reinforcement at a Splice

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

SPIRAL

////////A

LAP

4.4A

4.4B

<^6mm min. SPIRAL
@100mm min. PITCH

\\\\\\\\\\\\\

Efl

<—

U-A

SECTION A A

4.4C

Fig. 4.4 Possible Forms of Transverse Reinforcement at a Splice

!•

LAP 1

IsLAP

i, Ml

Fig. 4.5 Staggering of Lap Splices

bars above and below the offset shall be
parallel to the axis of the column. Adequate
horizontal support at the offset bends shall
be treated as a matter of design, and shall
be provided by metal ties, spirals, or parts of
the floor construction. Metal ties or spirals
so designed shall be placed near (not more
than 8 ^) from the point of bend. The
horizontal thrust to be resisted shall be
assumed as P/^ times the horizontal com-
ponent of the nominal force in the inclined

HANDROOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T).|9»7

Ld OR 30^

WHICHEVER IS
GREATER

IN FLEXURAL TENSION WITHOUT HOOKS

(ANCHORAGE VALUE OF HOOK OR
BEND + STRAIGHT LENGTH )

< L^ OR 300, WHICHEVER IS

' T^N GREATER.

STRAIGHT LENGTH

i 15(> OR 200
WHICHEVER IS GREATER

.N FLEXURAL TENSION WITH HOOKS

^d OR 2^0

WHICHEVER IS
GREATER

^ « DIAMETER OF SMALLER BAR

IN COMPRESSION
4.6A BARS IN TENSION AND COMPR! SSLON

Fig. 4.6 Lai* Li-NCiin {Oiniinucii)

HANDBOOK ON CONCRKTK RKINKORCKMKNT AND DKTAII INC;

SP : 34(S&T)-1987

ONE MESH4>100mm«2 END OVERHANGS ,
LAP TIP TO TIP OF WIRE

50 — »^ N m^ H 50

. vi *ii y

ILi I

TRANSVERSE WIRE

LONGITUDINAL WIRE

MORE THAN HALF STRESS END AND EDGE LAPS

TRANSVERSE
WIRES

ONE MESH^SOmm^

END LAP TIP TO TIP

OF WIRE

ONGITUDINAL WIRES

HALF STRESS END LAP

TRANSVERSE
WIRES

50 mm, EDGE LAP C/C
OF SELVAGE WIRE

HALF STRESS EDGE LAP
4.6B WELl>ED WiRE FABRIC

Fig. 4.6 Lap Length

portion of the bar {see Fig, 4.7). Offset bars
shaU be bent before they arc placed in the
forms. Where column faces are offset 75 mm
or more, splices of'vertical bars adjacent to
the offset face shall be made by separate dowels
overlapped at specified about.

N(n>: It h lo be noted that in Kig. 4.7, additional
stirrups will be required only near the bottom crank.

Bars of ilifferenl tiiameters — V^ hen bars
of two different diameters are to be spliced,
the lap length shall be calculated on the
basis of diameter of the smaller bar.

4.4.2.1 Lap spikes in welded wire fabric

a) The fabric is supplied in long mats/ rolls and
it is rarely necessary to have a joint of the
main wires. The rigidly connected cross-
members provide mechanical anchorage.
Adet^uate lapping where necessary may be
provided with a comparatively short lap
when cross wires occur within the lap.

b) In structural slabs, laps in regions of inaxt-
mum stress shall be avoided. Such splices,
where used for either end or edge laps,
shall be made so that the distance between

HANDBOOK ON CONCRETK RKINKORCKMKNT AND DKTAIUNC

SP : 34(S&T>-1987

HORIZONTAL COMPONENT
OF THE FORCE IN THE
INCLINED PORTION TO
BE TAK^N BY LINKS
AT *A*

NO LINKS
ARE REQUIRED
AT 'B'

OUTER FACE
OF COLUMN

1 IN 6 (max.)

LAP
LENGTH

CONSTRUCTION
JOINT

Fig. 4.7 Splice with Offset Cranked Bar in a Column

handbook on concrete reinforcement and detailing

SP : 34(S&T>.1987

outermost cross wires is not less than the
spacing of the wire parallel to the lap plus
100 mm (see Fig. 4.6).

c) In other cases for end laps, welded wire
fabric shall be lapped not less than one mesh
plus 50 mm, that is, the length of the lap
shall be 50 mm greater than the spacing of
wires parallel to the lap. For edge laps, a
lap of 50 mm is sufficient {see Fig. 4.6).

d) These requirements for lapping should be
covered by suitable notes in the general
specifications. But whether specified by
wordings or shown on plans, certain dis-
tinction should be made between *edge laps*
and *end laps*.

c) The width of an edge lap shall be indicated
as the centre-to-ccntre distance between the
outside of longitudinal salvage wires of the
overlapping sheets as illustrated in Fig. 4.6.

The length of an end lap shall be indicated
as the top-to-top distance between the ends
of the longitudinal wires of the overlapping
sheets.

4.4.3 Welded Splices and Mechanical Con-
nections — Where the strength of a welded splice
or mechanical connection has been proved by
tests to be at least as great as that of the parent
bar, the design strength of such connections shall
be taken as equal to 80 percent of the design
strength of the bar for tension splice and 100
percent of the design strength for the compression
splice. However, 100 percent of the design
strength may be assumed in tension when the
spliced area forms not more than 20 percent of
the total area of steel at the section and the splices
are staggered at least 600 mm centre-to-centre.

The choice of splicing method depends mainly
on the cost, the grade of steel, the type of
reinforcement, generally high bonding, the
possibility of transferring compressive and/ or
tensile stresses and the available space in the
section concerned. The designer shall specify the
splicing method and the conditions under which it
is to be carried out.

Mechanical coupling devices shall be arranged
so that as small a number as possible affect a
single section. They ihould, in addition, be placed
outside the most lughly stressed sections.

4.4.3.1 Sleeve splicing — \{ correctly used,
sleeve connections may transmit the total
compressive or tensile stress. In general, the use of
these sleeves is governed by various conditions
laid down in the agreement for the method or, in
the absence of recommendations, by preliminary
testing.

During assembly, particular care shall be taken
to ensure that the lengths introduced into the
sleeve arc sufficient.

These lengths should be marked before hand on
the ends of the bars to be spliced except when a
visual check on penetration is possible (for
example, sleeve with k central sight hole):

a) Threaded couplers (see Fig, 4,8) — In order
to prevent any decrease in the end sections
of the bar as a result of threading (with V-
form or round threads), they can be:

^1;3

^1:3

Fig. 4.8 Threded Couplers (Threading Limited
TO The Ends of Bars)

1) upset;

2) for long units, fitted with larger section
threaded ends by flash welding; or

3) fitted with a threaded sleeve by crimp-
ing.

Another solution consists of threading the
ends but only taking into consideration the
nominal section of the threaded end, that is,
reducing the permissible stress in the
reinforcement.

The ends of the sleeve shall be slightly
reduced in section in order to prevent
overstressing of the first few threads.

There are, at present, reinforcing bars
with oblique, discontinuous, spiral ribs,
allowing splicing with a special sleeve with
internal threads.

This same process is used to splice
prestressing bars, and in order to prevent
confusion between reinforcing bars and
prestressing steels, the direction of threading
is reversed (see Fig. 4.9).

flUlf4l^

Fig. 4.9 Coupler for Reinforcing Bars
(<^20 TO <^28)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SF : 34<S&T)-I987

Two lock nuts, tightened on each side of
the sleeve into which the reinforcing bars are
introduced to the same depth, prevent any
accidental unscrewing due to slack in the
threads (splices not under tension). The nuts
are tightened with a torque wrench.

This device is also used for splicing
prefabricated elements.

These joints are generally 100 percent
efficient under both tension and
compression.

To decrease the in-situ operations, one of
the ends is generally fitted with its sleeve in
advance and the other bar to be joined
with the sleeve should remain manoeuvrable
until the splice has been made {see Fig.
4.10).

b) Coupling with a crimped sleeve — Crimped
sleeves constitute a method of splicing
limited to relatively large diameter deformed
reinforcing bars. It consists of the
introduction of the bars to be spliced into a
sleeve which is crimped by means of a
hydraulic crimping tool onto the ribbed bars
in order to fill the voids between them and
the inner surface of the sleeve. The ribs on
the bar penetrate into the relatively softer
steel of the sleeve and the ribs work in shear.

During crimping the sleeve lengthens, and
the other reinforcing bar to be spliced
should be displaceable at this moment. The
size of the crimping device requires a bar
interspacing of at least 10 cm {see Fig.
4.11).

Splicing by crimping is also possible with
reinforcing bars of differing diameter. The
same method also enables threaded steel
rods to be spliced to reinforcing bars, using
high strength threaded bolts {see Fig. 4.12).

c) Coupling with injected s/eeves — These
couplings are a special case of sleeve
splicing; the stresses are distributed by the
shear strength of the product injected
between the ends of the bars to be sleeve
spliced:

1) With the Thermit' sleeve the space
between the deformed bars and the sleeve,
whose internal surface is also ribbed, is
filled with a special molten metal. This
molten metal is prepared in a crucible,
which is in communication with the
sleeve, by igniting a mixture consisting
mainly of iron oxide and aluminium
powder. The strength of the sleeve may
be increased by using a larger sleeve
diameter (see Fig. 4.13).

The sleeve is shorter but wider than
that used in the crimping method. The
bars are not in contact.

The splice may be made in any
direction as long as space allows the
crucible to be put into place.

2) Similar method is the injection of grout
or an epoxy resin between the sleeve and
the bars. The length of the sleeve is
necessarily greater (see Fig. 4.14).

d) Butt splices — For this purpose open
flanged sleeves made from steel strip can be
used. They are tightened onto the bars by
the introduction of a flat tapered wedge {see
Fig. 4.15).

The end sections, in contact within the device,
shall be perfectly at right angles to the axis of the
spliced bars.

Another method involves the use of 4 small
diameter ribbed bars which are tightened, using
pliers, with 3 ring-clamps. The advantage of this
method, in comparison to the previous one, is the
fact that it allows a portion of the tensile stress to
be taken up.

For bars with ribs in the form of a thread, a
butt splice may be made with a sleeve, but with
greater facility.

There are also sleeves consisting of a metallic
cylinder, the internal diameter of which fits the
bars to be spliced. This sleeve is fixed to one of
the reinforcing bars by a few welding points: a
hole at the centre of the sleeve enables one to
check that there is contact between the bars. This

Fig. 4.10 Splicing with Threded Couplers

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SV : 34(S&T)-1987

Fig. 4.11 Crimped Sleevs

V//^L//////// /'

1. crimped sleeve

2. reinforcement bar

3. sleeve

4. threaded bolt

5. internal thread

6. concrete

7. sleeve crimped on to
the bar and embedded in
concrete

Fig. 4.12 Sleeve Crimped on to a Threded Rod

economical method of splicing, which is easy to
apply, can only transmit compressive stresses.

4.4.3.2 Main advantages and disadvantages
of mechanical coupling

a) The use of mechanical couplers is frequently
justified when space does not allow lapping,
although crimping and tightening tools re-
quire accessibility which may reduce this
advantage.

b) This splicing method often requires more
careful cutting of the reinforcing bar, a
check which is more difficult than in the
case of lapping* it also requires the use of
reinforcing bars of the same diameter, and
mobility of one of the two bars to be spliced.

c) Good perforoiance of the splice is not
endangered by special atmospheric condi-
tions as in welding.

d) The cost of equipment and its use limit this
method to exceptional cases only.

Note — Some mechanical methods of splicing of rein-
forcement which are in vogue in this country make use of the
following principles:

a) A special grade steel sleeve is swaged on to reinforcing
bars to be joined with the help of a portable hydrauH-
cally operated bar grip press either at site or at stocking
yard.

b) Two sleeves with threaded ends are drawn together by an
interconnecting stud. These sleeves are then swayed on to
the reinforcing bars either at site or at the stocking yard.

4.4.3.3 Welded splices (or joints) — The
details of welding mild steel bars and cold-worked
steel bars in accordance with IS : 2751-1979 'Code
of practice for welding of mild steel plain and
deformed bars for reinforced concrete
construction {first revision)" and IS : 9417-1979
'Recommendations for welding cold-worked steel
bars for reinforced concrete construction*
respectively are covered in Appendix A,

4.5 Hooks and Bends

4.5.1 Hooks and bends, and other anchorage
of reinforcement in reinforced concrete shall be of
such form, dimensions and arrangement as will
ensure their adequacy without over-stressing the
concrete or steel.

4.5.2 Where normal hooks are used, they
should be of U-type or L-type; but usually U-type
is preferred for mild steel bars and L-type for
deformed bars. If the radius of the bend or hooks
conforms to that of the standard hooks or bends
in longitudinal bars, the bearing stresses inside the
bend in concrete need not be checked (see 4.5.2.1
and 4.5.2.2).

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T>-I987

2-A

1. deformed bar 4. vent-hole

2. grout 5. injection pipe

3. sleeve 6. spacer plug

Fig. 4.14 Splicing with Grouted Sleeves

\. deformed bar 8. iron oxide-aluminium mixture

2. prefabricated element 9. plugging disc

3. thermit sleeve 10. spliced length (±60 mm)

4. prefabricated element 11. thermit sleeve

5. msulation (asbestos) 12. bedding

6. ignition device 13. asbestos

7. crucible

Fig. 4.13 Thermit Sleeve

Fig. 4.15 Coupling with Sleeve and Wedge

4.5.2.1 Bearing stresses at bends — The
bearing stress in concrete for bends/ hooks in
stirrups and ties conforming to 4.3.5(b) need not
be checked as there is a transverse bar at each
bend. The bearing stress inside a bend in all other
cases should preterably be calculated as given in
the following formula {see Fig. 4.16). The most

dangerous situation is that of a bar, the layout of
which is parallel to a surface or wall. Safety can
be substantially increased by inclining the curve
.zone towards the mass of concrete wherever
possible, a condition which frequently occures in
anchorage. However, it may be noted that
IS : 456-1978 also exempts check for bearing

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

.0 ilFOR INTERNAL BARS) y

BEAM EDGE

FOR END BARS
SECTION-XX

4.I6A BEARING STRESS AT BENDS

TENSION

r ^0 456(|) (Vfck)(1 + 2*/a)

a( FOR END BARS)
U-a (FOR INTERMEDIATE BARS)

SECTION-YY

4.I6B MINIMUM INIERNAI, RADIUS OF BEND FOR EFFECTIVE
ANCHORAGE OF FULLY STRESSED TENSION BARS

Fig. 4. !6 Bearing Stress at Internal Bends

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&TVI987

stress in concrete for standard hooks and bends
described in Tabie 4 A.,

Beanng stress, a = — 7
r

where

Fbt - tensile force due to design loads in a bar
Of group of bars (N);

r - internal radius of the bend (mm); and

- size of the bar or» if in bundle, the size of
bar of equivalent area (mm).

For limit state method of design, this stress
1-5 U

shall not exceed

^^'

where /ck is the

characteristic strength of concrete and a, for a
particular bar or group of bars in contact shall be
t^ken as a centre-to-centre distance between bars
or groups of bars perpendicular to the plane of
the bend (mm); for a bar or group of bars

adjacent to the face of the member, a shall be
taken as the cover plus size of bar.

In other words, the minimum radius of the
bend, r, should be such that

«•«'*©(- f)

When the large steel stresses need to be
developed iw 'He bend, radial bearing stresses in
the concrete may become excessive. The above
equation controls the diameter of bend when
there is a combination of high tensile stress in the
bend, large bar diameter and low concrete
strength. To simplify the application of the above
formula minimum radius of bend is given in Table
4.5 for different grades of concrete and steel.

4.5.2.2 if a change in direction of tension or
compression reinforcement induces a resultant
force acting outward tending to split the concrete,
such force should be taken up by additional links

TABLE 4.5 MINBMUM RADIUS OF BEND FOR BARS FULLY STRESSED AT BENDS IN cm

{Clause 4.5.2.1)

Diameter

OF Bar in mm

N/mm^

a
cm

JL,

N/mm^

' 10

32 "^

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

250

2.5

13.7

17.9

27.7

39.5

57.0

86.6

5.0

10.6

13.5

19.9

27.4

38.0

55.4

7.5

9.6

12.0

17.3

23.3

31.7

45!

10.0

9.1

11.3

16.!

21.3

28.5

39.9

15.0

8.6

10.6

14.8

19.3

25.3

34.7

2.5

10.3

13.4

20.8

29.6

42.8

65.0

5.0

8.0

lO.l

14.9

20.6

28.5

41.6

7.5

7.2

9.0

13.0

17.5

23.8

33.8

10.0

6.8

8.5

12.1

16.0

21.4

29.9

15.0

6.5

8.0

11. 1

14.7

19.0

26.0

415

2.5

22.7

29.7

46.0

65.0

94.6

143.7

5.0

17.7

22.4

33.1

45.4

50.5

92.0

7.5

16.0

20.0

28.8

38.7

52.6

74.8

10.0

15.1

18.8

26.6

35.3

47.3

66.2

15.0

14.3

17.6

24.5

32.0

42.1

57.6

2.5

17.0

22.3

34.5

48.8

71.0

107.8

5.0

13.3

16.8

24.8

34.1

37.9

69.0

7.5

12.0

15.0

21.6

29.0

39.5

56.1

10.0

11.3

14.)

20.0

26.5

35.5

49.7

15.0

10.7

13.2

18.4

240

31.6

43.2

500

2.5

27.4

35.8

55.5

79.0

114.0

173.2

5.0

21.3

27.0

39.9

54.7

76,0

110.9

7.5

19.3

24.1

34.7

46.6

63.3

90.2

10.0

18.2

22.6

32!

42.6

57.0

79.8

15.0

17.2

21.2

29.5

38.5-

50.7

69.4

2,5

20.6

26.9

41.6

59.3

85.5

130.0

5.0

16.0

20.3

29.9

41.0

57.0

83.2

7.5

14.5

18.1

26-0

35.0

47.5

67.7

10.0

13.7

17.0

24.1

32.0

42.8

59.9

15.0

12.9

15.9

22.1

28.9

38.0

52.0

Note — The minimum radius is based on the full design stress in steel at the l>cnd. In the absence
of more precise calculations, it may be assumed that the tensile stress due to the anchorage at the source
of a hook is equal to half the stress on the bar, by reasons of its mechanical strength.

VIANDBOOK ON CONCRETE REINFORCEMENT AND DETAILINf

SP : 34(S&T)-I987

or stirrups. Accordingly in structural components
with curved or angled soffits, or those formed
with bends or corners, it should be ensured that
the radial tensile forces due to changes in the
direction of reinforcement are resisted by
additional links (see Fig. 4.17). Bent tension bar
at a re-entrant angle should be avoided.

4.17A TENSION BAR IN A CURVED SOFFIT

1 PROVIDE UNKS TO RESIST FORCE fl. TENSrON)
4.I7B COMPRESSION BAR IN HOGGING BEAM

i%i*

B) zSj

Fm'''

U AT ^ PROViOE LIMKS
TO RESIST FORCE N

ti) AT ® PROVIOE
\^. INTROOOS BAR

l'^ (SHOWN IN DOTTED
f LINE)

4.I7C COMPRESSION BAR IN A CORNER

Fig. 4,17 Radial Forces in Reinforcement

4.5.2.3 The minimum straight length of
hook is four times the bar diameter. For small
diameter bars this should be a minimum of
50 mm in order to facilitate holding the bar in
place while forming the hook. The hooks when
formed are quite large and while detailing it is
important to ensure that they do not foul with
other reinforcement, particularly where beams
have more than one row of bars.

4.5.2.4 Reinforcing bars shall be so deuiled
that the hooks are not positioned in tensile zones
of concrete as this may cause cracking. It is better
to bend the bars so that the hooks and bars
terminate in compression zones or so lengthen the
bars to eliminate the need for hooks.

4,6 Curtailment of Tension Reinforcement in
Flexural Members

4.6.1 For curtailment, reinforcement shall
extend beyond the point at which it is no longer
required to resist flexure for, a distance equal to
the effective depth of the member or 1 2 times the

bar diameter, whichever is greater, except at
simple support or end of cantilever. Figures 4.18
to 4.21 illustrate the requirement at cut-off point
and at supports in flexural members.

Note 1 — A point at which reinforcement is no longer
required to resist flexure is where the resistance moment of
the section, considering only the continuing bars, is equal to
the design moment.

Note 2 — The points at which reinforcement can be
curtailed is to be based on the bending moment envelope
developed by the designer. It should be noted that the use of
envelope helps in achieving better design. A typical bending
moment envelope considering various loading conditions
is given in Fig. 4.22.

Figure 4.23 gives a standard bending moment diagram
(based on uniformly distributed load) to enable designers to
choose locations for curtailment of reinforcement. In any
case the curtailment of reinforcement should fulfill the
requirements given in 4.6.1 to 4.6.4.

4.6.2 Flexural reinforcement shall not,
preferably, be terminated in a tension zone unless
any one of the following conditions is satisfied
{see Fig. 4.18):

a) The shear at the cut-off point does not
exceed two-thirds that permitted, including
the shear strength of web reinforcement
provided.

b) Stirrup area in excess of that required for
shear and torsion is provided along each
terminated bar over a distance from the cut-
off point equal to three-fourths the effective
depth of the member. The excess stirrup
area (mm^) shall be not less than 0.4 b s/f^,
v/here 6 is the breadth of beam (mm), s is the
spacing (mm) and /y is the characte.»-istic
strength of reinforcement (N/mm-). The
resulting spacmg shall not exceed (d'/8) pb
where p^ is the ratio of the area of bars cut-off
to the total area of bars at the section and J is
the effective depth.

c) For 36 mm and smaller bars, the continuing
bars provide double the area required for
flexure at the cut-off point and the shear
does not exceed three-fourths that permitted.

4.6.3 Positive Moment Reinforcement

a) At least one-third the maximum positive
moment reinforcement in simple members
and one-fourth the maximum positive
moment reinforcement in continuous
members shall extend along the same face
of the member into the support, to a length
equal to Ld/3 (see Fig. 4.18). where I^ is the
development length based on fully stressed
bars. This is required to provide for some
shifting of the moment due to changes in the
loading, settlement of supports, lateral
loads and other causes.

b) When a flexural member is part of a
primary lateral load resisting system, the
positive reinforcement required to be
extended into the support according to
(a) shall be anchored to develop its design

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

BARS SHOULD HAVE STANDARD 90 BEND, IF
REQUIRED TO BE BENT TO ACHIEVE L^yj

i 12<>0Rd* i

A5t

SIMPLE -^ i
SUPPORT

o
z

n
o

z
n

m
»

■n
O

w
z

INTERMEDIATE
SUPPORT

♦whichever is greater

A is the point at which certain amount of steel is no longer required
Any one of the conditions to be satisfied at the actual cut-off point, B:

^ SAGGING BENDING
MOMENT DIAGRAM

i) For bars <f^36 , -Ai^ lAi and

ii) Excess stirrup area (than that is required Irom design) in a distance of -^^ from the cut-off point along the terminated bar

Notations : A^_~ positive moment steel as per . actual design

Zi = development length based on fully stressed bars
V, = shear at the cut-off point

V — shear strength of the section
Ai = the critical area of steel required at the cut-off point
A2 — area of continuing steel

S = spacing of stirrups without cutting of steel

b = breadth of member

d = effective depth

/, = characteristic strength of reinforcement
area of bars cut-off

OAbs

with spacing > — -'A.

Bb =

Total area

Fig. 4.18 Tensile Development Lengths for Positive Moment Steel in Slab/ Beam with One Side Continuous and The Other
Discontinuous

stress (fuUy developed stress) in tension at
the face of the support {see Fig. 4.19).
This anchorage is to assure ductility of
response in the event of unexpected over-
stress such as from an earthquake. It is not
sufficient to use more reinforcement at lower
stresses. The full anchorage requirement
does not apply to any excess reinforcement
over and above that provided at the support.

c) At simple supports and at points of inflec-
tion, positive moment tension reinforcement
shall be limited to a diameter such that
Li does not exceed (see Fig. 4.18)

+ Lo

where

Ml - moment of resistance of the section
assuming ail reinforcement at the section
to be stressed to /a;

/d = 0.87 /y in the case of limit state design;

V - shear force at the section; and

Lo = sum of the anchorage beyond the centre
of the support and the equivalent ancho-
rage value of any hook or mechanical
anchorage at simple support; and at a
point of inflection, Lo is limited to
the effective depth of the members or
12<^, whichever is greater.

The value oi MxjV in the above expression may
be increased by 30 percent when the ends of the
reinforcement are confined by a compressive
reaction. In routine design calculations, it may be

found that -rr^ ^i

and hence no further check

need be made. When the requirement

is not satisfied, the designer should either reduce
the diameter of bars, whereby L^ is reduced, or

WITH

STANDARD 90'' BEND
OR BARS

SP : 34(S&T)-1987

increase the area of positive reinforcement at the
section considered, whereby M\ is increased, or
resort to both the steps.

4.6.4 Negative Moment Reinforcement — At
least one-third of the total tension reinforcement
provided for negative moment at the support shal!
extend beyond the point of inflection (PI) not less
than the effective depth of the member or 12 <^ or
one-sixteenth of the clear span, whichever is
greater {see Fig. 4.20 and 4.5 1).

4.7 Spacing of Reinforcement For the
purpose of this clause, the diameter of a round
bar shall be its nominal diameter, and in the case
of bars which are not round or in the case of
deformed bars or crimped bars, the diameter shall
be taken as the diameter of a circle giving an
equivalent .effective area. Where spacing
limitations and minimum concrete cover are
based on bar diameter, a group of bars bundled in
contact shall be treated as a single bar of diameter
derived from the total equivalent area.

4.8 Bars Bundled in Contact

4.8.1 General — Bars in pairs, or in groups of
3 or 4 tied together and in contact side by side
(boundled bars) may be ised in beams and
columns. This has been the practice in USA for
many years, and is now permitted in most
countries including India.

As bundled bars provide more reinforcement in
less space than do single bars, ii is possible to
reinforce a member more heavily and stilt get
better compaction of concrete. Beam and column
sizes can thus often be reduced with saving in
cost.

Bundled bars shall not be used in members
without stirrups. Bundled bars shall be tied
together to ensure the bars remain together as a
bundle. Bars larger than 36 mm diameter shall not
be bundled except in columns.

Whenever bar spacing limitations, minimum
cover, tie size and spacing are based on bar
diameter, a group of bars bundled in contact shall

Ast

EDGE COLUMN

4 *'ijs

INTERIOR COLUMN

L4 is development length based on fully stressed bars.
Fig. 4.19 Tensile Anchorage of Positive Moment Steel in Beams (When Beams are
Part of a Lateral Load Resisting System)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34<S&TM987

HOGGING BENDING
MOMENT DIAGRAM

COLUMN

•whichever is greater

A is theoritical cut-off point at which certain amount of reinforcement is no longer required

B is actual cut-off point

PI is point of infection

Fig. 4.20 Tensile Development Length for Negative Moment at Continuous Edge

— -

^ ^

/•Ast

12^ OR d*

rf )

4 \ "

LfiEAM Ofi SLAB
^t Ld

Ut^

COLUMN

* V.

♦Whichever is greater

Fig. 4.21 Tensile Development Lengths for Positive Moment Steel at
Discontinuous Ends

be treated as a single bar of diameter derived from
the total equivalent area {see Table 4.6).
However, the cover provided should be measured
fronn the actual outside contour of the bundle.

Note I — Unless patented splices are used, the bundling
of bars in columns is not recommended, as alt joints have to
be staggered. However, even when patented splices are used
the necessary staggering of splices makes assembly difficult
and prefabrication cumbursome.

Note 2 -- It is recommended to limit the bundle only to
two bars or three bars as four bars many times do not tie
into a stable bundle.

4.8.2 Development Length — Ld of each bar
of bundled bars shall be that for the individual
bar, increased by 10 percent for two bars in
contact, 20 percent for three bars in contact and
33 percent for four bars in contact. The

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

, »M ^ »N ^ »N lOM
(II <2l 13) U

REDISTRIBUTED MOMENTS (30%)

Fig. 4.22 A Typical Bending Moment Envelope

TABLE 4.6 EQUIVALENT BAR SIZE FOR BARS IN GROUPS

{Clause 4.8.1)

Bar

Size

2 Bars

3 Bar

Bundled

Equivalent ^ ^
size

Bars

i<t>)

4 Bar

s "^

' Area

Equivalent ^
Size

^ Area

Area

Equivalent ^
size

(2)

^3)

(4)

(5)

(6)

(7)

mm2

mm^

mm'

157

236

314

226

339

453

402

603

804

509

763

1017

628

942

1257

760

1 140

1520

982

1473

1963

1231

1847

2463

1608

2412

3 216

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

PERCENTAGE OF BEAM LENGTH
40 30 20 10

PERCENTAGE OF BEAM LENGTH
to 30 30 40

*18

C/5
ftp

'-J

iO 30 20 10

PERCENTAGE OF BEAM LENGTH

SPAN
CENTRE

10 20 30 40

PERCENTAGE OF BEAM LENGTH

Fig. 4.23 Standard Bending Moment Diagrams (Based on UDL)

SP : 34<S&T)-1987

anchorages of the bars of a bundle can only be
straight anchorages.

4.8.3 Curtaiiment — Bars in a bundle shall
terminate at different points spaced apart by not
less than 40 times the bar diameter except for
bundles stopping at a support {see Fig. 4.24).

4.8.4 Spacing — In case of bundled bars,
lapped splices of bundled bars shall be made by
splicing one bar at a time, such individual splices
within a bundle shall be staggered. For bundles of
2, 3 or 4 bars, the staggering distance should be
1.2, 1.3 and 1.4 times the anchorage length of the
individual bars respectively.

4.24A BUNDLE OF BARS CARRIED TO A SUPPORT

•"♦/I

OC-AOf / I C0.«^ /^

M '^' m

TMiORETICAt ^

cuT-orr Pom

4.24B BUNDLE TERMINATED AT THEORETICAL CUT

OFF POINT

STAGGERING ALL BARS

4.24C BUNDLE TERMINATED AT THEORETICAL CUT

OFF POINT

LAST PAIR TERMINATED SIMULTANEOUSLY

Fig. 4.24 Curtailment of Bundled Bars

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 5

Bar Bending Schedule
(Including Do's and Dont's in Detailing)

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-I987

SECTION 5

BAR BENDING SCHEDULE (INCLUDING DO'S AND
DONT'S IN DETAILING)

5.1 Bar bending schedules are very important
out of detailing and should give the following
information:

a) Identification of the structural member(s),

b) Position of the bars in the structure,

c) The bar mark,

d) The diameter or size of bar,

e) The number of bars of one type in each
structural member,

The total number of bars of each type,

g) the total straight length of the bar,

h) The shape and bending dimensions of the
bar,

j) The details of bar chairs can also be in-
cluded, and

k) Remarks, if any.

5.2 Schedules

5.2.1 The reinforcement of slabs, beams and
other parts of structures may be effectively shown
on working drawings in a tabular form, known as
a schedule. The schedule is a compact summary of
the dimensions of the concerned structural part,
all the bars complete with the number of pieces,
shape and size, lengths and bending details from
which fabrication details may be easily worked
out. The dimensioning procedure for different bar
shapes as shown in Tables 5.1 to 5.7 may be
followed.

Note — The value of length is the length of straight bar
from which the actual shape will be bent or for a straight
bar, the length of (hut bar. This length will be equal to
the sum of individual overall lengths of the straight
portions of each shape

5.2.2 A schedule shall be supplemented with
diagrams and sketches wherever necessary. Where
bars of different dimensions are used, the exact
arrangement of the reinforcement shall be shown
by means of clear diagrams. No abbreviation or
symbol shall be used in a schedule without proper
explanation.

5.2.3 For small structures detailed on a single
sheet, the schedule may be placed in the upper left
corner of the drawing. For larger structures
requiring more than one drawing, the complete
schedule may appear on the last sheet of the
details, or if the size of the strucutre warrants,

separate schedules may be prepared for each unit
(foundation, abutements, piers, etc) on the
drawing covering that specific unit of the
structure.

5.3 Beams, Girders and Joists — Details of rein-
forcement for beams, girders and joists are usually
shown in schedules. The schedules should show
the number, mark and location of member;
number, size, position and length of straight bars,
number, size, position, bending details and total
length of bent bars and stirrups; size, shape and
spacing of bar supports; and any other special
information necessary for proper fabrication and
placement of the reinforcement (see Table 5.8).
Care shall be taken not to omit any controlling
dimension such as overall length of the bar, height
of the bent bar and location of bar with respect to
supporting menribers where the bar is not placed
symmetrically. The schedule should also include
special notes on bending and any special
information, such as the requirements of laps, two
layers of steel, etc.

5.4 Slabs — The reinforcement for slabs is
generally indicated on the plan, with details for
the various types of bent bars shown in a schedule
(see Table 5.8). The schedule shall be similar to
that for bars in beams, except that the number of
bars may also be obtained from the plan. Panels
exactly alike shall be given an identifying mark or
so specified in the schedule.

5.4.1 In skewed panels, bars shall be fanned to
maintain given spacing in the mid span.
Additional bars for reinforcing the openings shall
be as shown on plan [see Section 9).

5.4.2 In case of welded wire fabric sheet in
slab panels, a schedule may also be included in
the structural drawing indicating the mesh sizes
(length and width) and fitting details for welded
wire fabric sheets for different slab panels. A
typical schedule is given in Table 5.9.

5.5 Walls — The reinforcement for walls shall be
indicated on the plan, elevation and section with
the details for various types of bent bars shown in
schedule in a manner similar to that for beams
and slabs.

5.6 Columns — The reinforcement for columns
may be shown in a column schedule. Piles and
pile caps should be treated as separate units and
separate details or schedule or both may be
provided. The main schedule may be
supplemented with a smaller schedule for ties and

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNC

SP : 34(S&T).|987

TABLE 5.1 MEASUREMENT OF BENDING DIMENSIONS OF
BARS FOR REINFORCED CONCRETE

{Clause 5.2.1)

Ref

No.

Method of Measurement* of
Bending Dimensions

Approx Total

Length of

Bar (L) Measured

Along Centre

Linf

■" g g "

bJ U i ■■

.ffe^.

/+^

/+2/^

/+5

/+2ir

Sketch and

Dimensions to be

Given in Schedule

STRAIGHT

Noi i; I Where a hook/ bend is to be formed at right angles to the plane in which the bending sketch of the bar is drawn
in the schedule, the hook/ bend shall be indicated as below and marked either 'hook /bend up' or 'hook/ bend down':
Bend Hook up /: Bend/ Hook down ^^ .

Noii; 2 H and B refer to hook allowance anu Dend allowance respectively.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

Ref

No.

TABLE 5.2 MEASUREMENT OF BENDING DIMENSIONS OF BARS
FOR REINFORCED CONCRETE

(Clause 5.2 J)

Method of Measurement of
Bending Dimensions

Approx Total

Length of Bar (L)

Measured Along

Centre Line

Where C is more than
3D

A + C+E

If angle with horizontal
is 45'' or IcM, and/{ is
\2d or less
A + C+E+2H or
I+2H+C- >JcF=W
(If / is spedfied. A or
E is oinitted>

If angle with horizonU)
is 450 or less, and R is
lid or less

^ + c:, + C2 + £+F+2//
or/+Ci + Q+2//

(If / u specified. A, E
or F is omitted)

Sketch and
Dimensions
to BE Given
IN Schedule

t*a

{set Note 2)

{see Note 2)

Nod: i Where a hook/ bend is to be formed at right angles to the plane in which the bending sketch of the bar is draw.
in the schedule, the hook/ bend shall be indicated as below and marked either *hook/bend up' or *hook/bend dowr
Bend Hook up ^ — '^ Bend/ Hook down

Noii 2 The internal radius R shall be specified if it is other than standard hook and b^nd.

N(ni: 3 // and B refer to hook allowance and bend allowance respectively.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP :34(S&T)-1987

TABLE 5.3 MEASUREMENT OF BENDING DIMENSIONS OF BARS FOR
REINFORCED CONCRETE

{Clause 5.2.1)

Ref

No.

Method of Measurement ot
Bending Dimensions

Apfkox Total Length of

Bar iL) Measured Along

Centre Line

Sketch and Di-
mensions to be

Given in

Schedule

A + E-y2R~d

(See Notes 2
and 3)

A-^E-ViR-d+lB

(See Notes 2
and 3)

A + E-*/iR-d-i^2H

{See Nov^ts 2
and 3)

Noil 1 - Where a hookf bend is to be formed at right angles to the plane in which the bending sketch of the bar is drawn
in the schedule, the hook; bend shall be indicated as below and marked either *hook/bend up' or *hook/bcnd down':
Bond Hook up y . Bend; Hook down ,_

Nori 2 The internal radius R shall be specified if it is other than standard hook and bend.

Nori; } tl, B and ci refer to hok allowance, bend allowance and nominal size of bar respectively.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

TABLE S.4 MEASUREMENT OF BENDING DIMENSIONS OF BARS FOR
REINFORCED CONCRETE

{Clause 5.2.1)

Ref

No.

Method of Measurement
OF Bending Dimensions

Approx Total Length of

Bar (L) Measured Along

Centre Line

Sketch and Di-
mensions to be
Given in
Schedule

A + E^l- D+2H

k-A-^V

If angle with horizontal is 45'
or less

A-i- E

If angle with horizontal is 45°
or less and R is \2J or less
A + E+2H

If angle is ereaier than 45° and
R exceeds lid, A to be
calculated

If angle with horizontal is 45"
or less

A + B+C-^/I~2{R+d)

M angle is greater than 45° and
R exceeds 12c/, L to be
calculated

y«

(See Note 2)

{See Note 2)

(See Note 2)

/+2//

{See Note 2)

\o'i- I Where a hook bend is to be fo:med at right angles to the plane in which the bending sketch of bar is drawti in
the schedule, the hook bend shall be indicated as below and marked either 'hook/bend up' or hook/ bend down:
Bend Hook up ^ Bend Hook down ^

Noil " I'hc internal radtiis R shall be specified if it is other than standard hook and bend.

N<Mi ^ // and B refer to hook allowance and h<-nd allowance respectively. , ^ , ^ ^ ■ .

Noil 4 Dimensions V and >' should b^ practical dimensions to enable the angle ot the bend to be determmed.

HANDBOOK ON CONCRKTL RF.IM QIKEMENT AND DETAILING

SP : 34(S&T)-I987

TABLE 5.5 MEASUREMENT OF BENDING DIMENSIONS OF BARS FOR
REINFORCED CONCRETE

\Claus€ 5.2.1)

Rff

No.

METHOD OF Measurement
OF Bending Dimensions

Approx loTAL Length of

Bar {D Measured Along

Centre Line

Sketch andDimen-

sioNS TO BE Given

in Schedule

4Jt

A+E^-JS + lH+d

(See Notes I
and 2)

tLt

^ + £+35+2J+fi+/j'

(See Notes I
and 2)

A+E+C+2H

y,/c'-~ly- D

(See Note 1)

E^2{A- D + C-^H)

'^n

{See Note i)

1+2C+2H

2C+2E^-^i'^2H

{See Note I)

! h/ intnn.ii racmis ii siuili be spcciiicd il it is other than standard hook and bend.

//. H .ind ./ relet to hook allowance, bend ;illowancc and a nominal si/.e of bar respective.

f'.Q

H\NnBO>K ON CONfRKTK RKINKORCKMKNT Wn DFTAIMNf;

Ref

No.

SP : 34(S&T)-I987

TABLE 5.6 MEASIJRFMENT OF BENDING DIMENSIONS FOR BINDERS
STIRRUPS, LINKS AND THE LIKE FOR REINFORCED CONCRETE

{Clause 5,2.1)

MtTHOD OF Measurement
OF Bending Dimensions

'I'

»•>

Riinry

-E-

£5.

Approx Total Length of

Bar (L) Measured Along

Ckntrf I INt

2(A + F) + 4d

2{A + E) + 20d

2(/l + £^ + 28(y

2A + E+C+nd^B

2/t+^'+C+9(/+fl

4C + 24t/

4C+20f/

SKETtH AND DI-
MENSIONS TO BE

Given IN Schedule

{See Notes I and 3)

{See Notes 1 and 3)

(See Notes I and 2)

LLJ

{See Notes 1 and 3)

{See Notes I and 3)

Non- 1 Ihe internal radius R of the corners of binders, stirrups, etc, shall be speciHed if it is other than standard liook
and bend.

Noji 2 If the form of the bar is such that there may be doubt us to which is the inside of the bar, arrows should be

shown on the bending schedule and the dimension stated with the suffin Of) or ]D {outside or mside dimension).

Noil 3 B and c/ refer to bend allowance and nominal size of bar respectively.

HANDBOOK ON CONCRETE REINFORCEMKNT AND DETAILINC,

SP : 34(S&T)-1987

TABLE 5,7 MEASUREMENT OF BENDING DIMENSIONS FOR BINDERS, STIRRUPS, LINKS AND THE

LIKE FOR REINFORCED CONCRETE

{Clause 5.2.1)

Ref No.

Method of

Measurement of

Bending Dimf.nsions

Approx Total Lengths of

Bar (L) Measured Along

Centre Line

Sketch and Dimensions to be
Given in Schedule

l^ —

2A + 3D + 224i

(See Note)

2A + 3D + 22(i

(See Note)

Where P is not greater than D/5

N = number of complete and

fractional turns
D = internal dia
P = pitch of helix
d = size of bar

Note d refers to nominal size of bar.

bent bars, diagrams showing the arrangement and
bending of the ties, and any special feature of the
construction pertinent to the fabrication and
placing of the column reinforcement. In case of
rectangular column the reinforcement details may
be indicated with reference to framing plan. !n
case of square columns designed for bending and
axial load with unequal reinforcement in two
directions, detailed plan should be given showing
the reinforcement, the beams framing into the
column, and other salient reference lines so that
the bars are placed in correct places.

In addition to showing size and normal spacing
of column ties, the designer shall also show any
additional ties required for special conditions such
as splices, offset bends, etc.

5.7 Dowels and Bar Supports — Dowels and bar
supports, spacer bars, bar chairs, etc, should be
specifically listed on the structural drawing and
should be scheduled in that portion of the
structure in which they are first required so that
they can be delivered with the reinforcement and
are available for placement at proper time.
F votings dowels shall. be scheduled with footings
rather than in column schedules.

5.8 Other Structures -^ On some types of
structures, such as bridges, tanks, sewers and
conduits, and certain components of buildings
such as stairs, special procedure may be used and
adopted to the particular structure. The principal
object is to show the reinforcement in a simple,
clear and easy manner. This may be accomplished

HANDBOOK ON CONCRKTE REINFORCEMENT AND DETAILING

TABLE 5.8 TYPICAL BAR BENDING SCHEDULE FOR BEAMS, SLABS AND COLUMNS

iaause 5.3)

Mark and

Location of

Member

(see Key Plan)

(1)

Drawing
Refer-
ence

(2).

No. of
Member

Bar
Type

(4)

Bar

No.

^(5)

Bar
Size

(6)

Cutting

Bar
Length

(7)

No. OF

Bars per
Member

(8)

Total

No. OF

Bars

(9)

Total
Weight
OF Bars

(!0)

Detailed

(Dimensioned)

Sketch

(II)

Remarks
(12)

5b 4 Floor \
and

Drg No.

Stc...

S,(f>

40 cm

Sb 6

Bm 6 Floor I

ft, 7

ft 8

and

ft, 10

Drg No.
Stc...

B.fl

200 cm

5. = straight

bars without

hooks.

ft = Bent bar with hooks at both ends.

TABLE 5.9 TYPICAL SCHEDULE FOR SLAB USING WELDED WIRE FABRIC AS REINFORCEMENT

idause 5.4.2)

Mark and
Location

Member
(1)

Drawing

Referencl

(2)

No. OF
Mem-
bers/

Panels

(3)

Fabric
Desig-
nation

No. AS

per IS:

(4)

Fabric
Refer-
ence

(5)

NlMHI K
IN

Each
Mem-
ber/
Panel

(6)

Total
No.

(7)

Width

(8)

Length
(9)

Cutting
(10)

Remarks
(M)

Drg No.
Stc...

1.5 m

5 m

Mark Location

tion
5h 7, Floor 2

Hard -drawn
steel wire
fabric confom-

Sb 8

30fn

mgtoIS:1566-

1982

.Vw 10 Floor 2

Drg No.
Stc...

1.5 m

3.25 m

J^ ^

" 3.25^

H
V

SP : 34(S&T)-1987

by a small detailed sketch of each bar or type of
bar with a table of dimensions.

5.9 Schedule Layout — A typical form of
schedule for beams» slabs and columns is shown
in Table 5.8 and Table 5.9 shows another typical
form schedule for slab using welded wire fabric as
reinforcement. Also an example of typical bar
bending schedule is given in Table 5.10.

5.9.1 Internatioanal Standard *ISO : 4066-
1977 'Building and civil engineering drawings-
Bar scheduling' establishes a system of scheduling
of reinforcing bars comprising the following
aspects:

a) the method of indicating dimensions;

b) a code system of bar shapes;

c) a list of preferred shapes; and

d) the bar schedule form.

This standard is reproduced in Appendix B as a
supplement to the information contained in this
Section.

5.10 Dos and Dent's for Detailing
5. 1 0.1 Do's General

a) Prepare drawings properly and accurately.
If possible label each bar and show its
shape lor clarity.

b) Prepare bar-bending schedule, if necessary.

c) Indicate proper cover to reinforcement,

d) Decide location of openings hole and
supply adequate details lor reinforcement
around openings.

c) Commonly available si/e of bars and spirals
shall be used for reinforcement. For a single
structural member the number of different
si/es of reinforcement har should be
minimum,

The grade of reinforcement bars shall be
clearly mentioned in the structural drawing.

g) For mild steel plain bars U-type hooks and
for deformed bars L-type hooks may be
adopted. Deformed bars need not have
hook at their ends.

h) Bars shall have smooth curved edges at the
point of bend.

j) In case of bundled bars, lapped splice of
bundled bars shall be made by splicing one
bar at a time; such individual splices within
a bundle shall be staggered.

k) When reinforcement is left exposed for
future construction, it should be adequately
protected from corrosion and weathering
action.

m) Congestion of steel should be avoided at
points where members intersect and make

certam that all reinforcement shown can be
properly placed.

n) Make sure that hooked and bent bars can
be placed and have adequate concrete
protection.

p) Make sure that bent bars are not so large
and unwieldly that they cannot be trans-
ported.

q) Indicate all expansion, contraction and
construction joints on framing plans and
provide details for such joints.

r) Where a section is not on the same sheet as
the plan from which it is taken, use a clearly
defined system of cross-reference for loca-
tions of sections and details.

s) Show enlarged details at corners, inter-
sections of walls, beam and column joint,
and at similar special situations.

5.10.2 Do'a — Beams and Slabs

a) Where splices are provided in reinforcing
bars, they shall be, as far as possible, away
from the sections of maximum stress and
shall be staggered.

b) Where the depth of a beam exceeds 750 mm
in case of beams without torsion and 450
mm with torsion, side face reinforcement
shall be provided.

c) In two-way slab, reinforcement parallel to
the short span of the slab shall be placed in
the bottom layer at mid-span and in the top
layer at support.

d) AH spacing shall be centre-to-centre spacing
of bars.

e) Deflection in slabs beams may be reduced
by providing compression reinforcement.

Only closed stirrups shall be used for tran.s-
verse reinforcement for members subject to
torsion and for members likely to be sub-
jected to reversal of stress.

g) At beam-column intersections ensure that
the main beam bars avoid the main column
bars.

h) At beam-beam intersections, main reinforce-
ment may be so arranged that layers in
mutually perpendicular beams are at diffe-
rent levels.

j) To accommodate bottom bars, it is good
practice to make secondary beams shallower
than main beams, at least by 50 mm.

k) If it is required the beam cages may be pre-
assembled with splice bars.

5.10.3 Do's—Columns

a) A reinforced column shall have at least six
bars of longitudinal reinforcement for using
in transverse helical reinforcement.

HANDBOOK ON CONCRETE RF.INFORCEMENT AND DtTAILING

SP :34(S&T)-1987

TABLE 5.10 TYPICAI. KXAMI'I K Oh A BAR BKNDIIVC; SC HKDt I K

{C/ause 5.9)

MEMBER

<
Z

X o

*~ UJ

TOTAL LENGTH IN m

BAR OETAiLS

REMARKS

f^8

1^20

t*14

tflO

1^8

*16

SLAB a

2-90

34^80

>V '«

... ■. .

382

43%4

,r*K'. n» ^^y"ii^

0-90

10-80

snr-

S^O

6OS0

SiC ^tf*

0-85

9.35

» \s

170

18-70

17«

1-45

u«

__J

4-00

20-00

iOO

SLA8 b

2-80

3>60

2«0

4-27

51-24

-2^-XLJU*/-^^

h "^-

2^0

11-20

•V 2n

3-52

U-08

BEAM 11

625

1^50

«ife

883

L— ^

6-83

•fin '^^,., J13 .'►y VaS'

8-46

8^6

,,»♦ «, JJ^

883

8^83

sf""-^ «1._.$'^^

190

3-80

51 .«

2.80

5^0

3ie

5-80

11-60

It*

>S9

38^16

s03

COLUMN Bi

4.00

1200

,« %».-^

400

UOO

7» %y-^'

220

4-40

lit

1
24

2-20

4-40

JXJ^^^

1-31

15-72

r(3

129

2-58

grw"

TOTAL LENGTH INm/OlAMETER

2999

2T2!

47-42

3*0

1^60

5648

2400

WEIGHT (N kg/m

0-39S

0-223

2464

V2D8

W17

0-395

>578

TQTAL WEIGHT W kg/DIAMETER

118

I-

HANDBOOK^ON CONCRETE REINFORCEMENT AND DETAMJNG

SP:34<S&T)-I987

b) Spacing of longitudinal bars in column shall
be along the periphery of the column, as
far as practicable.

c) Column bars of diameters larger than
36 mm in compression can be spliced with
dowels at the footing with bars of smaller
sizes and of necessary area.

d) A dowel shall extend into a column, a dis-
tance equal to the development length of the
column bar and into footing a distance
equal to development length of the doweK

e) Keep outer dimensions of column constant,
as iar as possible, for re-use of forms.

Preferably avoid use of two grades of verti-
cal bars in the same element.

5. 1 0.4 Dom 's— General

a) Reinforcement shall not extend across an
expansion joint and the break between the
sections shall be complete.

b) Flexural reinforcement, preferably, shall not
be terminated in a tension zone. If such case

is essential, the condition as given in Section
4 shall be satisfied.

c) Lap splices shall not be used for bars larger
than 36 mm diameter except where welded.

d) Bars larger than 36 mm diameter shall not
be bundled.

e) Where dowels are provided their diameter
shall not exceed the diameter of the column
bars by more than 3 mm.

Where bent bars are provided, their contri-
bution towards shear resistance shall not be
more than half that of the total shear rein-
forcement.

g) Different types of reinforcing bars such as
deformed bars and plain bars and various
grades like 415 N/mm- and 215 N mm-'
should not be used side by side as this prac-
tice would lead to confusion at site. How-
ever, secondary reinforcement such as links
ties and strirrups may be of mild steel
throughout, even though the main steel
may be of high strength deformed bars.

h) Under no circumstances should the bending
of bars at welds be permitted.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SECTION 6
Foundations

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

SECTION 6
FOUNDATIONS

6.1 Types of Foundations — The following are
types of reinforced concrete foundations, the
particular type being chosen depending on the
magnitude and disposition of the structural loads,
and the bearing capacity of the ground.

a) Individual Column Footing — Generally
square in plan but some times rectangular
or circular.

b) Combined Footing — Combined footing is a
common footing to two or more columns in
a line. The placing of reinforcement depends
on the shape of the bending moment and
shear force diagrams considering the soil
pressure and the column loads on the
footing,

c) Strip Footings — Under columns or walls.

d) Raft Foundation — Covering the whole plan
area of structure, detailing being similar to
2~way reinforced solid floor slabs or flat
slabs.

e) Pile Foundations — This includes detailing
of pile cap and pile portion.

6.2 Cover — The minimum thickness of cover to
main reinforcement shall not be less than 50 mm
for surfaces in contact with earth face and not less
than 40 mm for external exposed face. However,
where the concrete is in direct contact with the
soil, for example, when a levelling course of lean
concrete is not used at the bottom of footing, it is
usual to specify a cover of 75 mm. This allows for
the uneven surface of the excavation. In case of
raft foundation, whether resting directly on soil or
on lean concrete, the cover for the reinforcement
shall not be less than 75 mm.

6.3 Minimum Reinforcement and Bar Diameter

— The minimum reinforcement according to slab
and beam elements as appropriate should be
followed, unless otherwise specified. The diameter
of main reinforcing bars should be not less than
10 mm.

6.4 Detailing Methods — Foundations should
normally be detailed diagrammatically in plan
and elevation.

6.4.1 In case of plan, show diagrammatically
the location of foundation reinforcement (similar
to slabs) as well as starter bars and stirrups (as for
columns). It is preferable for column and wall
dowels (starter bars), and the foundation
reinforcement to be shown on the same drawing.

6.4.2 In case of elevation, show diagram-
matically the location of reinforcement as for
beams.

In case of pile foundation, detailing of pile is
similar to that of columns and detailing of the pile
cap supporting on piles is similar to that of
footing.

An indication of the type of soil and its
assumed bearing capacity may be specified in the
drawing.

6.5 Individual Footings - Individual footings
{see Fig. 6.1) are generally square and support a
central column. Rectangular footings can be used
when the space is restricted in one direction.
Individual footings of circular and other shapes
can also be used. Figure 6.1 gives typical details of
a column footing.

6.5.1 Reinforcement Requirements Total
tensile reinforcement shall be distributed across
the corresponding resisting section as given below:

a) In one-way reinforced footing, the reinforce-
ment shall be distributed uniformly across
the full width of the footing.

b) In two-way reinforced square footing, the
reinforcement extending in each direction
shall be distributed uniformly across the full
width of the footing.

c) In two-way reinforced rectangular footing,
the reinforcement in the long direction shall
be distributed uniformly across the full
width of the footing. For reinforcement in
the short direction, a central band equal to
the width of the footing shall be marked
along the length of the footing and portion
of the reinforcement determined in accor-
dance with the equation given below shall be
uniformly distributed across the central
band:

Reinforcement in central band 2

Total reinforcement in short direction (y/ .x) + 1

where y is the long side and x is the short side of
the fooling.

The remainder of the reinforcement shall be
uniformly distributed in the outer portions of the
footing.

Figure 6.2 illustrates placing of transverse rein-
forcement for a rectangular footing.

HANDBOOK ON CONCRKTE REINFORCEMENT AND DETAILING

SI»:34(S&I)-I'>87

STARTER BARS

(STA&G£R SPUCINq'^
Ct

COLUMN BARS

SECTION-BB

5 -COLUMN BARS
STARTER BARS**
^COVERTOSTARTERUO)
_£ r75 KICKER

SEE NOTE BELOW

(OENERAUY}

UNLESS SPECfiED
USE^If 8(9300
ON0S.(MtN.)

(MIR)
LEVELING COURSE ABOVE SOIL

SECTIONAA

PLAN

L<h = Effective development lenth considering tension

Ujc = Effective development length considering compression

*NnT?^i'*TLidr«JnSrH"^o"\*'^!i' **«»J?nds upon the distance between the first floor level and the level of foundation.
Knr^ 7~ rn^^J !JltJx '*'"^' J^^ l^\^^' " '^"^""''^ *^ ^ ^^' "P^^^ds to fict the required development length.
Note 2 -In case a pedestal is provided, the development length is to be considered from the top level of pedestal.

Fig. 6. 1 Typical Details of a Column Footing

HANDBOOK ON CONCRETE REINFORCEMtNT AND DETAILING

SP : 34(S&T)-1987

»1

»J

•

^ , X/,

T-^i —

l^ SEE NOTE BELOW

h i i ■ t i

■ 1 al

SECTION-AA

\ ^

SECTION-BB

^•1 al U

*S2 1 K

n r

1 r

A,. A,,».

-LONBITUOINAL BARS

PLAN

Note — Provide standard 90** bend, if the bar is required to be bent upwards to get required development
length.

Fig. 6.2 Placing of Transverse Reinforcement for a Rectangular Footing

6.5.1.1 Vertical reinforcement or dowels —
Extended vertical reinforcement or dowels of at
least 0.5 percent of the cross-sectional area of the
supported column or pedestal with a minimum of
4 bars of 12 mm diameter shall be provided.
Where dowels are used, their diameter shall not
exceed the diameter of column bars by more than
3 mm.

Column bars of diameter larger than 36 mm in
compression can be dowelled at the footings with
bars of smaller size of the necessary area. The
dowel shall extend into the column a distance
equal to the development length of the column
bar, and into the footing a distance equal to the
development length of the dowel. The
development length shall be calculated in
accordance with 4.4.2.

For method of detailing see Fig. 6.1.

Note — Where the depth of the footing or footing and
pedestal combined is less than the minimum development
length in compression required foi dowels (starter bars) of a
certain size, the size of dowels (starter bars) may be suitably
decreased and the number of dowels increased to satisfy the
required area and development length.

6.5.1.2 To achieve economy, the footings
are sloped or stepped towards the edge satisfying
the requirements for bending and punching shear.
In sloped footing, the slope is generally restricted
such that top formwork is not called for in

construction. The thickness at the edges shall not
be less than 15 cm for footings on soils, nor less
than 30 cm above tops of piles in case of footing
on piles.

6.6 Combined Footings

6.6.1 Combined footings become necessary
where the external columns of the structure are
close to the boundry of an existing structure and
also where the footings of individual columns
overlap one another. Such foundations
(supporting more than one column/ pedestal or a
continuous wall) shall be proportioned to resist
the design loads and individual reactions, in
accordance with appropriate design requirements.
The detailing requirements as specified in Section
4 for slabs and beams shall be followed as
appropriate.

6.6.2 Detailing — For combined footing,
detailing of longitudinal and transverse bars is
similar to that of beams.

6.6.2.1 Column on edges of footing — To
prevent shear failure along the inclined plane
(corbel type of failure) in footing, where a column
is located on the edge, it is advisable to provide
horizontal U-type bars around the vertical starter
bars. These bars shall be designed for every such
column {see Fig. 6.3).

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&r)-1987

VERTICAL BARS FOR COLUMN
REINFORCEMENT

LPLANE OF SHEAR
FAILURE

U- TYPE BARS

SECTION

DEVELOPMENT LENGTH
IN TENSION

LU- TYPE BARS
PLAN

Fig. 6.3 Colimn on Edgh of a Footing

.6.6.2.2 Figure 6.4 (A, B and C) shows
typical arrangement of bars in combined footings.

6.7 Continuous Footing Under Walls — In

continuous wall foundations, transverse
reinforcement should be provided when the
projection of the footing beyond the wall exceeds
the thickness of the footing {see Fig. 6.5). it is also
recommended that longitudinal reinforcement be
provided wherever an abrupt change in the
magnitude of the load or variation in ground
support or local loose pockets may occur along
the footing.

6.8 Raft Foundations — A raft is a foundation
unit continuous in two directions, covering an
area equal to or greater than the base area of the
building. If the raft consists of several parts with
varying loads and heights, it is advisable to design
the raft with expansion joints between these parts.
Joints shall also be provided wherever there is a
change in the direction of the raft and should be
detailed on the drawing. The detailing

requirements as specified in Section 4 for beams
and columns may be followed as appropriate.

6.8.1 Minimum reinforcement in either
direction shall not be less than 0.15 percent of the
gross sectional area for mild steel reinforcement
and 0.12 percent in case of high strength
deformed bars.

6.8.2 Detailing — For raft foundation, detail
both the longitudinal and transverse bars
generally m accordance with the rules for slabs
and beams except cover and bar supports. While
detailing reinforcement in raft foundation,
construction method and sequence of
construction are to be specified which should
include the following:

a) Position of construction joints,

b) Position of movement Joints, and

c) Position of water bar joints.

The location of lap splices in raft should be
detailed with care as the direction of bending will
differ from suspended members.

6.8.3 Placing of Bar Supports Where top
reinforcement is required, consideration should be
given 10 the method of supporting this with chairs
and edge U-bars. This must be carried out in
accordance with the specification for the job and
should take into account construction sequence,
weight of top steel and depth of foundation. The
suggested spacing of supports is 30 times the
diameter of supporting bars using chairs having
diameter of at least !2 mm. I he diameter of
chairs should be such that they do not bend or
buckle under the weight of reinforcement and
other incidental loads during construction.

6.8.4 Ducts and Trenches — Where ducts and
trenches occur in rafts, special attention should be
given to detailing continuity of top reinforcement,
specially where moment transfer is required (see
Fig. 6.6).

6.9 Pile Foundation

6.9.1 Driven Precast Concrete Pile

a) The longitudinal reinforcement ^hall be
provided in precast reinforced concrete piles
for the entire length. All the main longitu-
dinal bars shall be of the same length with
lap welded at joints and should fit tightly
into the pile shoe if there is one. Shorter
rods to resist local bending moments may
be added but the same should be carefully
detailed to avoid any sudden discontinuity
of the steel which may lead to cracks during
heavy driving. The area of main longitudinal
reinforcement shall not be less than the
following percentages of the cross-sectional
ar-ea of the piles:

1) For piles with length less than 30 times
the least width— 1.25 percent.

H.\NDBOOK ON CONCRETE RtlNFORCEMENT AND DET.AIMNG

sr : 34(S& T)-1987

; -.c-

COLUMN

••••4--'---*.---'-*-

U-

tf- ->'•*•■•«■ liZ

ELEVATION

KEEPING STIRRUPS SnilClN6 pL
CONSTANT. VARY NO. OF LEGS f^

(3,^,6) OR KEEPING THE NO.
OF LEGS CONSTANT VARY
THE SPACING.

¥W7^

:£=

1 i 1 fc

• LEG.STPS.

■ ■ 11 i ■ I

.4-r V--:.:-. i>- -..

IW^

^=£

■ ■ ■■■till i

4 LEG.STPS.

-*-: . ,:^;. 4 <■■.:.:-»■>

SECTION -A A

SECTION -BB

6.4A COMBINED COLUMN KOOTING

COLUMN

jiL

,y.-.v..'^T,...

.■•H^.i-'-..-.v\>--.:--.-^~-^. ■•-.:■»■ *--^. ;■«•.. i--,|

.■..•A.r...rj.....^....'^..A

I-

STIRRUPS AT SUITABLE SPACING

U--

^ ^

'**••■ ■••-•*-•■--••• •-•••• ^-^

TRANSVERSE dENOING
REINFT.AT COLUMNSONLY.

StCTION-AA SECTION -BB

6.4B STRIP FOOTING UNDER COLUMNS

Fig. 6.4 Typical Details of Combined Footing {Continued)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

COLUMN A
-fl Vrr>-STARTER BARS

COLUMN B

QC
U

z
o
o

L^^

lift ft? Ill

LEVELING COURSE
5ECTI0N-BB

BOTTOM STEEL
UNDER COLUMN *A'

MAIN STEEL BARS
WITH NOS.

DISTRIBUTION BARS-"

BOTTOM STEEL ^
UNDER COLUMN *8^

PLAN- BOTTOM STEEL

DISTRIBUTION BARS

MAIN TOP BARS
WITH NOS.

PLAN- TOP STEEL

64C TAPtRED COMBlNtD FOOllNG S TlRliPPS.( NOT SHOWN)

Fig. 6.4 Typical Details of Combined Footings

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIMNG

SP : 34(SftThl9S7

«RM.l TIIICKNCSS

1 >D fyfj^

■

Wj^y

l"*^

M-4

mmnMJC^i

tt«}T«30oii 1

Fig. 6.5 Strip Fcx>ting Under Walls

2) For piles with length 30 to 40 times the
least width— 1.5 percent.

3) For piles with length 'greater than 40
times the least width— 2 percent.

b) The lateral reinforcement is of particular
importance in resisting the driving stresses
induced in the piles and should be in the
form of hoops or links and of diameter not
less than 6 mm. The volume of lateral rein-
forcement shall not be less than the
following {see Fig, 6.7):

1) At each end of the pile for a distance
of about 3 times the least width—not
less than 0.6 percent of the gross
volume of that part of the pile; and

2) In the body of the pile— not less than
0.2 percent of the gross volume of
pile.

The spacing shall be such as to permit free flow
of concrete around it. The transition between the
close spacing of lateral reinforcement near the
ends and the maximum spacing shall be gradually
over a length of 3 times the least width of the pile.

The cover of concrete over all the reintoroement
including ties should not be less than 40 mm. But
where the piles are exposed to sea water or water
having other corrosive content, the cover should
be nowhere less than 50 mm.

Piles should be provided with flat or pointed
co-axial shoes if they are driven into or throu|^
ground, such as rock, coarse gravel, clay with
cobbles and other soils liable to damage the
concrete at the tip of the pile. The shoe may be of
steel or cast iron. Shapes and details of shoes
depend on the nature of ground In which the pile
is driven. In uniform clay or sand the shoe may be
omitted.

Where jetting is necessary for concrete piles, a
jet tube may be cast into the pile, the tube being
connected to the pile shoe which is provided with
jet holes. Generally, a central jet is inadvisable^ at
it is liable to become choked. At least two jet
holes will be necessary on opposite sides of the
shoe, four holes give best results. Alternatively,
two or more jet pipes may be attached to the sides
of the pile.

6.9.1 .1 Reinforcement requirement — A
pile shall be reinforced in the same way as the
column, with the main bars on the periphery and
secondary bars (binders or links) around main
bars. In addition the main bars shall be bent
inwards at the lower end and welded to the shoe
made of chilled cast iron or steel.

6.9.1.2 Spacer bars ^To ensure the
rigidity, pile spacer bars shall be used as shown in
Fig. 6.8. The spacer bars or forks can be of cast
iron, pressed steel or a length of steel pipe with
slotted ends to fit the main reinforcing tars. They
can be detailed on the drawing, at 1.5 m centres
along the full length of the pile. The fork may be
placed diagonally at each positron across the
section as shown in Fig. 6.S.

iAP

' . I TRENCH

k-^ I

1 ' 11 • ■ I

LAP

ammm^^mmm^i^ml^iim^

Fig. 6.6 Typical Details Around a Trench in Raft Foundation

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNG

SP : 34(S&T)-I9S7

LATERAL STCCL
(MINIMUM)

0-6 PCRCaEMT

VOLUME Of THIS

PART OP PILE

TRANSITION

0-2 PERCENT OP
VOLUME OP
PILE

TRANSITION

0-e PERCENT

VOLUME OP THIS

PART OP PILE

30 3D

< ^i iuJ44 1 1 1 1 immiM

SPACING 0/2 max

LONGITUDINAL ST EEL, MINIM UM : 1-25PERCENT FOR I < 300

1*5 PERCENT FOR 300^1 $400
2*0 PERCENT FOR ( > iOD

Fici. 6.7 Minimum Steel Requirements of precast concrete pile

*» 32, LIFTING

HOL€

•^8 $& 70
L40mm COVER

*»8®70
TO UO

i" # 32

^8 @) UO
LONGITUDINAL SECTION

8 (3)70
TO UO

06 (§i 70

8 CLOSED
STIRRUPS

STEEL FORKS
IN PAIRS
(SPACER BARS)
32. LIFT HOLE

MS STRAPS

SHOE

SECTION A A

TOE FOR PILE
(SUITABLE FOR GRAVEL AND SAND)

Fig. 6.8 Typical Details of a Precast concrete pile

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAlllN(.

SP : 34(S&T>-1987

6.9.2 Cast-m-situ Piies or Bored Piles

6.9.2.1 Reinforcement requirement — The
design of the reinforcing cage vary depending
upon the driving and installation conditions, the
nature of the subsoil and the nature of load to be
transmitted by the shaft, that is, axial or
otherwise. The minimum area of longitudinal
reinforcement (mild steel or deformed bars)
within the pile shaft shall be 0.4 percent of the
sectional area calculated on the basis of outside
area of casing of the shaft.

The curtailment of reinforcement along the
depth of the pile, in general, depends on the type
of loading and subsoil strata. In case of piles
subject to compressive load only, the designed
quantity of reinforcement may be curtailed at
appropriate level according to the design
requirements. For piles subjected to uplift load,
lateral load and moments, separately or with
compressive loads, rt may be necessary to provide
reinforcement for the full depth -of pile. In soft
clays or loose sands, or where there is likelihood
of danger to green concrete due to driving of
adjacent piles, the reinforcement should be
provided up to the full pile depth with lap welds
at joints regardless of whether or not it is required
from uplift and lateral load considerations.
However, in all cases, the minimum reinforcement
should be provided in the full length of the pile.

Piles shall always be reinforced with a
minimum amount of reinforcement as dowels,
keeping the minimum bond length into the pile
shaft and with adequate projection into the pile
cap.

Clear cover to all main reinforcement in pile
shaft shall be not less than 50 mm. The laterals of
a reinforcing cage may be in the form of links or
spirals. The diameter and spacing of the same is
chosen to impart adequate rigidity to the
reinforcing cage during its handling and
installations. The minimum diameter of the links
or spirals shall be 6 mm and the spacing of the
links or spirals shall be not less than 150 mm.

6.9.3 Under-reamed Piles — The minimum
area of longitudinal reinforcement in stem should
be 0.4 percent. Reinforcement is to be provided in
full length. Transverse reinforcement shall not be
less than 6 mm diameter at a spacing of not more
than the stem diameter or 300 mm, whichever is
less. In under-reafmed compaction piles, a
minimum number </f four 12-mm diameter bars
shall be provided. For piles of lengths exceeding
5 m and of 375 mm diameter, a minimum number
of six 12-mm bars shall be provided. For piles
exceeding 400 mm diameter, a minimum number
of six 12-mm bars shall be provided. The circular
stirrups for piles of lengths exceeding 5 m and
diameter exceeding 375 mm shall be minimum
8-mm diameter bars.

The minimum clear cover over the longitudinal
reinforcement shall be 40 mm. In aggressive

environment of sulphiites, etc, it may be increased

to 75 mm.

Fi<:ure 6.9 gives typical details of a bored cast-
in-situ under-reamed pile foundation.

J/'

SIIRflUPS

FOfI MAKINO
PiRtt SULS

*-COVtR 7S TO 100

StCOMO/LAfT
•Ult

3A snCTiON OF SINGI E 3B SECTION OK MULTI
IJNDHK-RFAMEJ) PILE UNl^ER-REAMED PILE.

<^, - 45° (approx),
D„ = normally 1.5 D

4^2 ^ 30°-45« (Approx)

Fig. 6.9 Typical Details of Bored Cast in-situ
Under-Reamed Pile Foundation

6.9.4 Pile Caps

6.9.4.1 The pile cap usually supports
column and this is positioned at the centre of
gravity of the pile group, so the pile cap
incorporates column dowel bars in exactly the
same way as provided in column bases. Allowance
shall be made in length and width of the cap to
allow for piles being slightly out of true position
after being driven.

6.9.4.2 General consideration — The pile
cap alongwiih the column pedestal shall be deep
enough to allow for the necessary anchorage of
the column and pile reinforcement. Although they
are assumed to act as a simply supported beam
and are designed for the usual conditions of
bending moment and shear force, there is a
tendency to fail in bursting due to high principal
tension. This should be resisted by reinforcement
going around outer piles in the group (usually
n \2 @ 150).

Generally adopted configuration for pile caps
alongwith plan arrangement of reinforcement
details are shown in Fig. 6.10.

6.9.4.3 The clear overhang of the pile cap
beyond the outermost pile in the group shall
normally be 100 to 150 mm, depending upon the

pile size.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34<S& r)-l987

HORIZONTAL TIES TO
RESIST BURSTING

MAIN STEEL

NOMINAL
STEEL

FOR 2 PILES

—

«.»•

—

r—

i— ]

^ 1

^1
^1

• ^ «

• ^^

■ '^4

For 4.5,6.8 and 9 PILES

FOR 7 PILES

* MAIN STEEL

FOR 3 PILES

— ^-«« NOMINAL STEEL

Fig. 6-10 Generally Adopted Configuration for Pile Caps
(Along with Plan Arrangkmfnt of Reinforcement)

6.9.4.4 A levelling course of plain concrete
of about 80 mm thickness may be provided under
the pile caps, as required.

6.9.4.5 The clear cover for the mair.
reinforcement for the bottom of cap shall not be
less than 60 mm.

6.9.4.6 The reinforcement from the pile
should be properly tied *o the pile cap.

6.9.4.7 A typical arrangement of bars in a
pile cap supporting a column between two piles is
illustrated in Fig. 6,1 1 and typical details of a pile
cap resting on 3 piles is illustrated in Fig. 6.12.

6.9.5 Grade Beams

6.9.5.1 The grade beams supporting the
walls shall be designed taking due account of
arching effect due to masonry above the beam.
The beam with masonry behaves as a deep beam
due to composite action.

6.9.5.2 The minimum overall depth of grade
beams shall be 150 mm. The reinforcement at the
bottom should be kept continuous and an equal
amount may be provided at top to a distance of
quarter span both ways from pile or footing
centres as the case may be. The longitudinal
reinforcement both at top and bottom should not
be less than three bars of 10 mm diameter (mild
steel) and stirrups of 6 mm diameter bars spaced
at a maximum spacing of 300 mm (see Fig. 6.13).

6.9.5.3 In expansive soils, the grade beams
shall be kept a minimum of 80 mm clear off the
ground. In other soils, beams may rest on ground
over a levelling concrete coarse of about 80 mm
(see Fig. 6.14).

6.9.5.4 In case of exterior beams over piles
in expansive soils, a ledge projection of 75 mm
thickness and extending 80 mm into ground {see
Fig. 6.14), shall be provided on outer side of
beams.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-IW7

HORIZONTAL TIES TO
RESIST BURSTING
(USUALLY H* 12 0110)

IL I

STARTER BAR

CLEAR OVERHANG
rOENERALLY 100T01SO

SHEAR
REINFT.

PILE
BARS BEND AT STANDARD
9Cr BEND TO GET REQUIRED
DEVELOPMENT LENGTH

SECTION- A A

^■■^

:.%;•■.*

*-dJL TOP STEEL

<IP REQUIRED)

J T '"- '!

*y%

GRADE
BEAM

SECTION-BB

■

'—

'"'"■

^"•a

b...

.„*

— ^

ff\

^1 1

A 1

') i

T I

_____

. «.■

»—- -

.i-* w. .

;

PLAN • BOTTOM STEEL

Note — In a 2-piIe system, sufficient care shoukl be token to transfer bending in the transverse direction.

Fig. 6.11 Typical Details of a 2-Pile Cap

HANDMOK ON CONCRETE REINFORCEMENT AND DETAIUNG

SF : 34(S&T>-t9S7

CLEAR 0VEIIHAN6
100 TO 150 -1

4 ■

STARTER BARS

BINDING STEEL AROUND
PILE BARS

SHEAR REINFT,

75 COVER

IIYM!l?.£gy5!£ LuMLESS SPACIFIEO

LEAN CONCRETE ^ io Q 300 ( 3 NOS.MINJ
SECTION- A A

BAR BENT AT 90^ STANDARD
BEND TO GET THE REQUIRED
DEVELOPMENT LENGTH

BOTTOM
MAIN BARS

BINDING STEEL AROUND
PROJECTED PILE BARS

PLAN

Fig. 6^.12 Typical Details of a 3-Pile Cap

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAiUNG

SI»;34(S&I>I»>H7

COVER 7$

1/4

£=*

i300

.Atl (NOHINAl,
(F NOT DESIGNEd

SPLICE AT CENTRE OF SUPPORT
IF REOUIRED

LAP SPLICES AT MID
J ^ SPAW, iF REQUIRED

F00TIH6

Fig. 6.13 Typuai. Longmudinai, Six tion of a Gradi: Hi am
i WIDTH OF WALL ,

BRICK WALL

' "^^mfi?^

11 • m

^^^^

*• ■■..■■•.■■■ ■■." ■'■■■■ i^,-'- •■•■.•':■■■■•>'.■;*-•:

.:">- •*•■'::• -■•■;-.>;.--.v-'-,.-i.f

LEVELING COURSE

6.I4A bi:ams in noni xtansivi: sons

WIDTH OF WALL

^ * " ^ 1

^#/jm' ^

WIDTH OF WAU

SO mm THICK CONCRETE
OR BRICK ON EDGE

6.I4B BEAMS !N tXPANSIVP SONS

Fig. 6.14 Typical Sj-xtions of Grade Beams

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAlI.INC;

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 7
Columns

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(Sft1>19t7

SECTION 7
COLUMNS

7.0 General — Reinforced concrete columns are
used to transfer the load of the structure to its
foundations. These ate reinforced by means of
main longitudinal bars to resist compression
and/ or bending; and transverse steel (ties) to
resist bursting force.

The column or stmt is a vertical compression
member, the effective length of which exceeds
three times its least lateral dimension.

7.1 Longftudinal Reinforcement

7.1.1 In a reinforced column, the area of
longitudinal reinforcement shall not be less than
0.8 percent nor more than 6 percent of the gross
cross-sectional area of the column.

The area of longitudinal reinforcement should
normally not exce^ 4 percent of the gross cross-
sectional area of the column. This percentage can
be considered as the maximum from practical
considerations.

However where bars from one column have to
be lapped with those of another column above,
the total maximum percentage of 6 percent may
be allowed at the lapping. Proper placing and
compacting of concrete should be ensured at the
place of lapping.

7.1.2 A minimum number of 4 bars shall.be
provided in a column and six bars in a circular
column with helical reinforcement.

7.1.3 The bars shall be not less than 12 mm in
diameter and spacing ol the bars along the
periphery of the column shall not exceed 300 mm.

7.1.4 In the case of pedestals in which the
longitudinal reinforcement is not taken 4nto
account in strength calculations, nominal
longitudinal reinforcement of not less than 0.15
percent of the gross cross-sectional area shall be
provided.

Noit — Pedesul is a compression member, the effective
length of which docs not exceed 3 times the least lateral
dimension.

7.1.5 Dowels and Bar Suppom — I>owels
aiid bar supports, spacer bars, oar chairs, etc,
should be specifically listed on the structural
draviring and should be scheduled in that portion
of the structure in which they are first required so
that they can be delivered with reinforcement and
are available for placement in time. Footing
dowels shall be scheduled with footings rather
than in column schedules (see Section 6 for
requirements of dowels in footing).

7.2 Tnmsvene Rdnforccmer^

7.2.1 A reinforcement concrete compression
member shall have transverse or helical
reinforcement so disposed that every longitudinal
bar nearest to the compression face has efTective
lateral support against buckling. The effective
lateral support is given by transverse reinforce-
ment either in the form of circular rings capable
of taking up circumferential tension or by
polygonal links (lateral ties) with internal angle
not exceeding 135**.

7.2.2 Arrangement of Transverse Reinforce'
m^m — Where the longitudinal bars are not
spaced more than 75 mm on either side,
transverse reinforcement need only to go round
comer and alternate bars for the purpose of
providing effective supports (see Fig. 7.1).

bu=$:

tr-TQ

£L

^75

<75

Fig. 7.1

7JJ If the longitudinal ban spaced at a
distance not exceeding 48 times the diameter of
the tie are effectively tied in two directions,
additional longitudinal bars in between these bars
should be tied in one direction by open ties {lee
Fig. 7.2).

Fig. 7.2

HANDBOOK ON CONCRETE ITClNFORCEMENT AND DETAILING

SP : 34(S&T)-I987

7J.4 Where the longitudtnat reinforcing bars
in a compression member are placed in more than
one row, effective lateral support to the longitu-
dinal bars in the inner rows may be assumed to
have been provided if:

a) transverse reinforcement is provided for the
outermost row, and

b) no bar of the inner row is closer to the
nearest compression face than three times
the diameter of the largest bar in the inner
row {see Fig. 7.3).

Uii

OIAMCTER ^

Fig. 7.3

12S Where the longitudinal reinforcing bars
in compression member are grouped (not in
contact) and each group adequately tied with
transverse reinforcement in accordance with 7.2.1,
the transverse reinforcement for the compression
member as a whole may be provided on the
assumption that each group is a single
longitudinal bar for purpose of determining the
pitch and diameter of the transverse reinforce-
ment in accordance with 7.2.1. The diameter of
such transverse reinforcement need not, however,
exceed 20 mm {see Fig. 7.4).

TRANSVeRSE REINFORCEMENT

A few examples of column ties are illustrated in
Fig. 7.5.

7 J.6 Pitch and Diameter of Lateral Ties

7J.6.1 Pitch — The pitch of the transverse
reinforcement shaH not be more than the least of
the following distances {see Fig. 7.6 A):

a) the least lateral dimension of the compres-
sion member,

b) sixteen times the smallest diameter of the
longitudinal reinforcing bar to be tied, and

c) forty eight times the diameter of the trans-
verse reinforcement.

7.2.6.2 Diameter — The diameter of the
polygonal links or lateral ties shall not be less
than one-fourth of diameter of the largest
longitudinal bar, and in no case less than S mm.

7.2.7 Helical Reinforcement (Spirally Rein-
forced) {see Fig. 7.6 B).

7.2.7.1 Pitch — Helical reinforcement shall
be of regular formation with the turns of the helix
spaced evenly and its ends shall be anchored
properly by providing one and a half extra turns
of the spiral preferably with a 135° hook. The
pitch of the helical turns shall be not more than
75 mm or one-sixth of core diameter of the
column, nor less than 25 mm or 3 times the
diameter of steel bar forming helix. Tension lap
length shall be provided at lap splices.

Note — It is important to note that when the ratio of the
volume of helical reinforcement provided to the volume of

the core is greater than 0.36 I — p - 1 J ^ , the strength

of the compression member may be increased by 1 .05 times
the strength of similar member with lateral ties.

where

gross area of the section.

INDIVIDUAL GROUPS
Fio. 7.4

A^ - area of the core of the helically reinforced column
measured to the outside diameter of the helix,

/ck ^ characteristic compressive strength of the concrete,
and

fy = characteristic strength of the helical reinforcement
but not exceeding 415 N/mm^

7^.7.2 Diameter — The diameter shall be
not less than one-fourth of the diameter of the
largest longitudinal bar, and in no case less than 5
mm.

7.2.8 Temporary Stirrups — At least two
temporary fixmg stirrups should be provided to
hold splices in position {see Fig. 7.7) or to stiffen
the helically bound columns during fabrication. It
is better to detail and schedule such stirrups in the
drawing. The stirrups coming above the floor
shall not be removed until the next column is
erected.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

-» 1

' 1

i5N

SINOIC TIC

SIN8I.E TIE

I^hS"

TWO TICS

J'^^K

SP : 34(S&T>-1987

V^W

(TTr

»ir

OMC TIC AND
ONC LINK

TWO TICS AND
TWO LINKS

TWO TIES

ONC TIC AND
TWO LINKS

TWO TICS

THRCC TICS

i%n_i<7\

fTl

TWO TIES

THREE TIES

FOUR TICS

THRCC TICS

^ p ]

c^^ .

I <

t L _j

TWO TICS AND ONC LINK

, .,,

« !

HRCC TICS Al

40 ONC UNK

Jk /v < /»

□

>7S^

r--^

• >5

If-?

L ,

WALL - LIKC COLUMN

| ,^**»tr,|

WALL -LIKC COLUMN

l^aia

5^ ■

» 4

' -5

-* c a

RTT — F

I !■

$ «»#1r

CORNER COLUMN CORNER COLUMN

7 5A LATERAL TIES AND LINKS

Fig. 7.5 Typical Arrangement of Column Ties {CommueO)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I9«7

■"

1 '^

L J J

7.5B EXAMPLES Oh ARRANGING BUNDLE BARS IN COLUMNS

Fig. 7.5 Typical Arrangement of Column Ties

,L,CgVERJOTlES

mm.
^ PITCH (P)
(least of b,

LATERAL TIES

.longitudinal

BAR

01 < 12

mm.

^COVER TO LON GITUDINAL
^BATTZOmm*

7.6A RECTANGULAR COLUMN

•Cover can be reduced to 25mm when
a ^ 200» b < 200 and A = 12.

COVER TO TIES

— ■ »

£OVER TO L0N6ITU0(NAL
AR « iOmm')^

/•PITCH (P)

>75mm
<i25mm

I* 302 J

CONTINUOUS TTE
(SPIRAL)

7 6B CIRCULAR COLUMN

•Cover can be reduced to 25 mm when
D^200 and 0= 12

Fig. 7.6 Bar Spacing Requirements in Columns

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T>-tfS7

TEMPORARY
FiXtMG STIRRUPS
(TO MAINTAIN BARS IN
POSITION DURING CASTING)

EXTRA STIRRUP&IF NOT
WITHIN BEAM OR SLAB

DOUBLE STIRRUPS
AT CRANK

MAIN COLUMN BARS

MAIN COLUMN STIRRUPS

Fig. 7.7 Temporary Fixing of Stirrups

7.2.9 Large Columns -~ Where reinforcement
for very wide columns is to be fabricated in
.separate cages artd erected in sections, they should
be held together by at least 12 mm diameter bars
spaced at double the stirrup spacing {see Fig. 7.8),
Special requirements, if any, should be indicated
by the designer.

7.3 Splicing of Column Reinforcement

7.3.1 General — Splicing is normally effected
by the lapping of bars. The lengths of laps in the
main bars shall conform to the values given in
Section 4 (Tables 4.2 to 4.4). The bottom of the
bars are normally at floor level. In exceptional
cases, the bars mat extend over more than one
storey, provided that check is made to ensure that
intersecting steel from beams, etc, can be placed
through the column without difficulty, that the
column reinforcement can be properly supported,
and the concrete can be properly placed. Some of
the bars terminating below floor level require
separate splicing (see also Section 4). Typical
splice details are shown in Fig. 7.9 (A to E) for
both internal and external columns.

7.3.2 Where a column at a particular floor is
smaller (in cross-section) than the column
immediately below it. the vertical bars from the

lower column shall be offset to come within the
upper column, or dowel shall be used. The slope
of the inclined portion shall not exceed 1 in 6. In
detailing offset column bars, a bar diameter
should be added to the desired offset; and in the
corner of the square columns, the bars should be
offset along the diagonal.

7.3.3 Longitudinal reinforcement bars in
square or rectangular columns should be offset
bent into the column above. Longitudinal bars in
round columns where the column size is not
changed should be offset bent if maximum
number of bars are desired in the column above.
The general practice is to sketch the offset for the
corner bars which should be bent diagonally and
make this the typical offset dimension for all the
bars in the column.

7 J.4 For offset between column faces up to a
maximum of 75 mm, the longitudinal bars should
be offset bent. When the offset exceeds 75 mm,
the longitudinal bars in the column below should
be terminated at the floor slab and separate
dowels used (see Fig^ 7.9 B and 7.9 D).

7J.5 Where adjoining beam is not provided,
the height of the column equal to say 75 mm
above the- floor level should be cast along with the
lower column so that a kicker can be formed to
place the column shutters (j^^e Fig. 7.9C).

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

3 SEPARATE CASES

Fio. 7.8 Reinforcement in Cages for Long Columns

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

IP ^ TOP COLUMN
OBUT BARS

EXTRA TIES AT
THE POINT OF BEND

LOWER COLUMN BARS

FIXING TIES CAN BE
REMOVED BEFORE
ERECTING CAGE OVER

COLUMN BARS

SLOPE 1 IN G (MAX.)

LOWER BARS CRANKED
INTO THE POSITION INSIDE
UPPER BARS

DOWEL BARS

FIXING TIES TO BE
REMOVED BEFORE
ERECTING CAGE OVER
DOWELS

(THE CROSS SECTIONAL
AREA OF THE DOWELS
MUST BE SAME AS THE
BARS ON THE UPPER
COLUMN.

■ ri I

7.9A SPLICE WITH LOWER BARS CRANKED INIO
POSITION INSIDE UPPER BARS (INTERMEDI-
ATE FLOOR)

79B SPLIClNCi AT THE ELOOR LEVEL WHEN THE
RELATIVE DISPLACEMENT OK COLUMN LACES
IS MORE THAN 75 MM

7.3.6 When the bar arrangement changes
between floors, bars may extend through, stop
off, or require separate dowels (Fig. 7.9 B). Each
situation requires its own solution. Steel equal to
an area and bond capacity to that in the column
above shall be extended. Column bars shall be
spliced at the top of upstand beams, if available,
rather than at floor level.

7.3.7 Where the column verticals are offset
bent, additional ties/ spirals shall be provided {see
Fig. 7.10) and placed at a distance not more than
8 bar diameters from the point of the bend. For
practical purpose, 3 dosely spaced ties are usually
used, one of which may be part of the regularly
spaced ties plus two' extra ties. The designer shall
indicate on the drawing the general arrangement
of vertical bars and all tie arrangements.

The number of additional ties/ spirals should be
designed on the assumption that the horizontal
thrust to be resisted shall be 1.5 times the
horizontal components of the normal stress in the
inclined portion of the bars.

7.3.8 Welded splice or other positive
connections may be used as butt splices for

vertical column bars instead of lapped splices. For
bars of size 32 mm and above, such splices or
connections may be used to avoid overcrowding
of the bars due to extremely long laps which
would otherwise be required. Special preparation
of the ends of the vertical bars is usually required.
Where bars are welded, the most common
practice is to provide a square-cut end at the top
and a double bevelled end on the bottom of the
upper bar to rest on the square cut end {see Fig.
7.1 1). This permits filling the resulting space with
weld metal to develop the splice. Where a welded
sleeve or a mechanical device is used, both ends of
the bar may be either square cut or standard shear
cut, depending upon the type of connection used.
Since the point of splice is to be staggered
between alternate vertical bars and the splice
location will depend upon the design
requirements, the designer should indicate the
types of splice permissible and their location on
the drawing.

7.4 Bundled bars shall be tied, wired or
otherwise fastened to ensure that they remain in
position. End-bearing compression splices should

HANDBOOK ON CONCRETE REINFORCEMENT ANo DETAILING

SP : 34(S&T>-I987

be held concentric, all bundles of column verticals
should be held by additional ties at each end of
end-bearing splices, and any short splice bars
added for tension should be tied as part of the
bundle within the limit of 4 bars in a bundle. A
corner of a tie should be provided at each bundle.

7.5 Column in Flat Slabs — Mushroom heads
are normally cast with the columns, and the
details of reinforcement should be such that the
steel can be formed into a separate cage.
Therefore, it should be ensured that the column
stirrups end below the mushroom head to enable
a properly bonded cage to be positioned (see
Fig. 7.12).

Note — 7 he designer shall determine the amount of steel
required in the mushroom to control cracks arising from the
out-of-baiance moments.

7.6 Column-Beam Junction — Typical details of
a * column-beam junction are illustrated in
Fig. 7.13.

At column-beam intersections, it is better to
avoid main beam bars clashing with main column
bars.

If splice bars are used (see Fig. 7.13), the beam
cages may be prefabricated and splice bars placed
in position after the beam reinforcement has been
positioned in place. This also provides
considerable scope for positioning support bars
without resorting to cranking and avoiding
intersecting beam and column reinforcement.
However, this detail requires extra steel due to the
additional laps.

Where the beam does not frame into the
column on all four sides to approximately the full
width of the column, ensure that the stirrups are
provided in the column for the full depth of the
beam, or alternately, that special U-bars are
detailed with the beam to restrain the column bars
from buckling and to strengthen the concrete in
compression. This is especially important where

DOWEL 9AR
COLUMN 8AR

LJ'^OOWELBAR

VCOLUMN BAR

SLOPE
1:6(MAX.)

FIXING TIES TO BE
REMOVED BEFORE
ERECTING CAGE OVER

«75

i=-

FIXING TIES TO BE
REMOVED BEFORE
ERECTING CAGE OVER

SLOPE
1:S(MAX.)

7.9C. SPIKE WITH UPPER BARS CRANKED INTO
POSIIION INSIDE LOWER BARS

7.9D SPLICE WITH THE LOWER BARS CRANKED
INTO A POSITION INSIDE THE UPPER BARS
WHEN THE RELATIVE DISPLACEMENT OF
COLUMN FACES IS LESS THAN 75 MM

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

FIXING TIES TO
BE REMOVED
BEFORE ERECTING
CAGE OVER
(SEE NOTE)

lyTlMCS THE HORIZONTAL
COMPONENT OF THE FORCE
m THC INCLINEO PORTION
OF THE 8AR TO BE TAKEN
BY ADDITIONAL TIES,
PLACED NOT MORE THAN
B<fr FROM THC POINT OF
BEf« AT

ADDITIONAL
TICS TO BE
WITH IN THIS
ZONE

COVER

STIRRUPS THROUGH

BEAM COLUMN

JUNCTION

(SEE CLAUSE 7.6}

Fig.

SLEEVE

7.10 Splice with Ofiset Crankkd Bar
IN A Column

TWO ADDITIONAL
SETS OF TfPtCAL

TIES PROvioeo

AT EACH END

WELI

A. END BEARING COMPRESSION
SPLICE

B. WELDED BUTT SPLICE
TENSION/COMPRESSION

7.9E Splicing when the Lower Bars Cranked into a Position
inside the Upper Bars with Stepping of Columns on
One Side

Note — It is important to note that splices should be
staggered within the cc^ui^in

Fig. 7.9 Splicing of Column Bars at
Intermediate Floors

the floor concrete is of a weaker grade than the
column concrete {see Fig. 7.14 and 7.15).

In general, it is advisable to use U-bars at the
non-continuous ends of beams of depth greater
than 600 mm.

Note — It is important to note that a joint by itself
shall have a dependable strength sufficient to resist the
most adverse load combinations sustained by the adjoining

Fig. 7.11 Typical Details of Butt Splices

members as specified by the appropriate loading code A
higher factor of safety is sometimes necessary for joints.
Design and detailing of the joint should be done to satisfy
this condition.

7.7 Column with Corbel Joints

7.7.1 Corbels — A corbel is a short cantilever
beam {see Fig, 7.16) in which the principal load is
applied in such a way that the distance between
the line of action of the load and the face of the
supporting member is less than 0.6d and the depth
at the outer face of the bearing is greater than
one-half of the effective depth at the face of the
supporting member.

7.7.2 Main Reinforcement — The main
tension reinforcement in a corbel should be not
less than 0.4 percent and not more than 1.3
percent of the section at the face of the supporting
member, and should be adequately anchored.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

50 (STEP)

CONCRETE CAST TO
HERE BEFORE PLACIN0
MUSHROOM CA6E

CIRCULAR COLUMN

Fig. 7.12 Reinforcement of Mushroom Heads

COLUMN BARS STRAIGHT
THROUGH JUNCTION

STIRRUP HANGER
8ARS STOP SHORT
OF COLUMN FACE

PRIMARY
BEAM

TOP BAR$» PRIMARY
BEAM BARS PLACED
ABOVE SECONDARY
BEAM

SECONDARY BEAM

BOTTOM BARS STOP
SHORT OF COLUMN FACE

BOTTOM SUPPORT BARS

BOTTOM BARS STOP SHORT OF COLUMN FACE

Fig. 7.13 Beam-Column Intersection

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T).1987

lSHEAR
STIRRUPS

COLUMN TIES

7.14A F-iXED END JOINT IN A COIUMN

•' ■■ "■ ->^

vROl

■

T 1

f y

^b <i4

~-\-

ROOF LEVEL

Fig. 7.15 Typical Details or a Bham-Coli'Mn
Junction at Exterior Column

a
a

hy > h/2

Fig. 7.16 Truss Anology for CoRmT DiskiN

MAIN STEEL

J l ^t IBARD IA.

7.I4BTERMI
A SLAB

natioAj

B /

OF COLUMN BARS INSIDE

Fig. 7.14 Typical Details of End Joints in a
Column

Anchor the reinforcement at the front face of the
corbel either by welding it to a transverse bar of
equal stength or by bending back the bars to form
loops; in either case, the^ bearing area of the load
should not project beyond the straight portion of
the bars forming the main tension reinforcement
{see Fig. 7.17 and 7.18).

-MAIN STEEL 0AP
^ELC

TRANSVERSE BAR OF
EQUAL STRENOTH
WEVfiCOTOMAINSTOL

NOMINAl STEEL FOR
ANCHOMNB STIRRUPS

SHEAR REINFORCEMCMT

Fig. 7.17

HANDBOOK ON CONCRETE REINFORCEiMENT AND DETAILING

SP : 34(S&Ty-1987

Note — The limitation on reinforcement percentages
is based on the limited number of tests available.

7.7.3 Horizontal Force — When the corbel is
required to resist a horizontal force in direction H
applied to the bearing plate (see Fig. 7,19) because
of shringkage or temperature changes, provide
additional reinforcement to transmit this force in
its entirety. This reinforcement should be welded
to the bearing plate and adequately anchored
within the supporting member.

7.7.4 Shear Reinforcement — PTO\i6c shear
reinforcement in the form of horizontal stirrups
distributed in the upper two-thirds of the effective
depth of the corbel at the column face. This

reinforcement should have an area of at least one-
half of the area of the main tension reinforcement
and should be adequately anchored (see Fig.
7.19).

7.8 Detailing of Reinforcement — Columns
should be detailed by means of enlarged views.
Indicate the levels of the bottom (top of bars at
floor level) and top of the column (at top of slab
or beam or upstand beam) and the floor height, if
necessary. Indicate on the schedule the- positions
of all intermediate beams. Show each bar mark
once, and provide adequate sections showing all
main bars and the arrangement of stirrups. Keep
in view the effect of providing kickers on levels.

MAIN STEEL IN THE
FORM OF LOOPS

4 1 BAR 01 A

SHEAR
REINFORCEMENT

NOMINAL STEEL FOR
ANCHORING STIRRUPS

l-d IN COMPRESSION

MAIN STEEL

SHEAR

REINFORCEMENT
EXTRA STIRRUPS

Fig. 7J8

Fig. 7.19

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SECTION 8
Beams

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-i98'

SECTION 8

BEAMS

8.1 Arrangement of Bars — The main consider-
ation when arranging bars in beam is to obtain
the most economical layout to satisfy the design
requirements. It shall also satisfy the relevant
rules concerning horizontal and vertical spacing
of bars and required bottom and side covers.
While fixing the overall dimensions of beams,
slenderness limits for beams to ensure lateral
stability and span-to-depth ratios to control
deflection, shall be kept in view.

The following points shall also be noted in
detailing {see Fig. 8.1).

a) The bars shall be symmetrically placed
about the vertical centre line of the beams.

b) Where there are only two bars in a row, these
shall be placed at the outer edges.

c) Where bars of different diameter are placed
in a single bottom row, the larger diameter
bars are placed on the outer side.

d) Where bars in different horizontal rows have
different diameter, the larger diameter bars
shall be placed in the bottom row.

8.2 Longitudinal Reinforcement

8.2.1, Minimum Distance Between Individual
Bars — J\\t following rule shall apply:

a) the horizontal distance between two parallel
bars shall be usually not less than the
following:

1) diameter of the bar, if the diameters are
equal;

2) diameter of the larger bar, if the dia-
meters are unequal; and

3) 5 mm more than the nominal maximum
size of coarse aggregate.

Note — This does not preclude the use of larger size
aggregates beyond the congested reinforcement in the same

MIN. COVER

2SmmORf»

Q O

tt4

Q P O D

MIRHOmZOMWl SWCINC -3— I

frf

O Q

o o

MIN. VERTICAL SPACmc

ii.lC '

A r

Q p' a p

-I ^

o o o o a:
o o o o a:
Q Q q in sf-

cnn

MIN. VERTICAL SMCM
»y»»«0R#0R1Smm*

8.IE

MM. HORIZONTAl SPACING
•UROCRBAROIA.OR
8.ID (•^♦5inm.)»

#-WHICMCVCRI$6RCATER
fm DIAMETER OF THE BAR

k^.NOMINAL/MAX.SIZE OF A86RE0ATE

Fig. 8.1 Minimum Clearance Between Individual Bars

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

Mm.M0RI20HTAl SFACINO
•lAROER BAR DIA.Oflth.*Stom)*

SP : 34(S&TM987

member, the size of aggregate may be reduced around
congetted reinforoemem to comply with this provision.

b) Greater horizontal distance than the mini-
mum specified in (a) should be provided,
wherever possible. However, when needle
vibrators are employed, the horizontal dis-
tance between bars of a grou{> may be
reduced to two-thirds of the nominal maxi-
mum size of aggregate, provided vibrator
can be used without difficulty.

c) Where there are two or more rows of bars,
the bars shall be vertically in line and the
minimum vertical distance between bars
shall be 15 mm or two-thirds the nominal
maximum size of aggregate or the maximum
size of the bar, whichever is the greatest.

The minimum spacing requirements of reinfor-
cing bars in beams is illustrated in Fig. 8.1 and
Fig. 8.2.

8.2.2 Tension Reinforcement

8.2.2.1 Minimum reinforcement — The
minimum area of tension reinforcement shall not
be less than that given by the following:

At, Min =

0.85 bd

where

At = minimum area of tension reinforce-
ment,

b = breadth of the beam or the breadth of
the web of T-bcam,

d = effective depth, and

/y == characteristic strength of reinforce-
ment in N/mm2.

8.2.2.2 Maximum reinforcement — The
maximum area of tension reinforcement shall not
exceed 0.04 bD, where b is the width oi the beam
rib or web and D is the total depth of the beam.

8.2.2.3 Maximum distance between bars in
tension — Unless the calculation of crack widths
shows that a greater spacing of bars is acceptable,
the following requirement should be fulfilled for
control of flexural cracking:

The horizontal distance between parallel
reinforcement bars, or groups near tension
face of a beam shall not be greater than the
value given in Table 8.1 depending on the
amount of redistribution carried out in
analysis and the characteristic strength of
:he reinforcement {see Fig- 8.3).

MIN. COVER

•EQUIVALENT DIAMETER
OR25mm.WHICHEVER
IS GREATER

VERTICAL SPACING

HORIZONTAL SPADNG

«.2A VERTICAL PAIRS

HORIZONTAL SPACING

2B HORIZONTAL PAIRS

Uw VERTICAL
SPACING

L. HORIZONTAL SPAaNG

8.2C BUNDLES

VERTICAL SPACING SHOULD
BE NOT LESS THAN IS mm
OR 2/3 hg OR # WHICHEVER
IS GREATER.

HORIZONTAL SPACING SHOULD
BE NOT LESS THAN ( h^^ Smm)
OR EQUIVALENT DIAMETERS

li« s NOMINAL/MAX. SIZE OF AGGREGATE
<p « EQUIVALENT DIAMETER OF BAR

100

Fig. 8.2 Minimum Spacing Between Groups of Bars

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP :34(S&T)-1«)87

SIDE FACE
REINFORCEMENT

(St« clause 82*4)

I ;^3000Rb
PREFERABLY ^
WITHfN 2o -Tf

i>300 0Rb
L_

NOT GREATER THAN THE
VALUES SPECIFIED IN TABLE 8-1

Fig. 8J Reinforcement Spacing Rules for Crack Control

TABLE 8.1 MAXIMUM CLEAR DISTANCE BETWEEN
TENSION BARS

Percentage Redistribution to or From
Section Considered

-30

-15

+ 15

+30

Clear Distance Between Bars

N/mm^

250

215

260

300

415

125

155

ISO

210

235

500

105

130

150

175

195

Note — The spacings given in the table are not applicable
to members subjected to particularly aggressive environ-
ments unless in the calculation of the moment of resistance,
f, has been limited to 300 N/mm^ in limit state design.

8.2.3 Compression Reinforcement ~ The
maxim uin area of compression reinforcement
shall not exceed 0.04 bD. Compression
reinforcement shall be enclosed by stirrups for
effective restraint. The anchorage length of
straight bars in compression shall be equal to the
development length of bars in compression.

8.2.4 Side Face Reinforcement — ^here the
depth of the web in a beam exceeds 750 mm side
face reinforcement shall be provided along the
two faces. The total area of such reinforcement
shall be not less than 0. 1 percent of the web area
and shall be distributed equally on two faces at a

spacing not exceeding 300 mm or web thicknes-
whichever is less {see Fig. 8.4).

8.3 Detailing of Shear Reinforcement

a) A stirrup in the reinforced concrete beam
shall pass around or be otherwise adequately
secured to the outer most tension and
compression reinforcement, and such stir-
rups should have both its ends anchored
properly in any one of the fashion detailed
in Fig. 8.5. In T-beams and I-beams, such
reinforcement shall pass around longitudinal
bars located close to the outer face of the
flange.

SIOC FACE REINFORCE*
MEKT SHALL K PROVIDEO
WHENtHCOCPTHOFWEB
EXCEEDS 7SQ mm (0S%
OF WEB AREA ON EACH
FACCI

:^kOR^O0mm
wmtCHEVER IS LEAST

Fig. 8.4 Side Face Reinforcement in Beams

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

101

SP : 34<S&T)-I987

U — 8«»

8.5A

8.5B

8.5r
Fig. 8.5 Different Ways of Anchoring Ends of Stirrups

While adopting stirrups, different shapes
(see Fig. 8.6) may be considered depending
on constructional requirements keeping in
view the end anchorage requirements. How-
ever, while choosing a particular shape for a
particular situation, its validity should be
considered from structural point of view.

b) Benhup Bars — Tensile reinforcement which
is inclined and carried through the depth of
beam can also be considered to act as shear
reinforcement provided it is anchored in
accordance with 4.3.5 {see Fig. 8.7).

Usually two bars are bent up at a time at an
angle 45*^ to 60° to the longitudinal axis of

the beam but other angles can also be
adopted.

It is usual practice to combine bent up
bars and vertical stirrups to resist the
shear since some of the longitudinal bars
are bent up when they are no longer requi-
red at the bottom {see Fig. 8.7).

c) Maximum Spacing — The maximum spac-
ing of shear reinforcement measured along
the axis of the member shall not exceed
0.75 d for vertical stirrups and d for inclined
stirrups at 45°, where d is the effective depth
of the section under consideration. In no
case shall it exceed 450 mm.

102

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-W87

PI n n

® ® ®

"♦u

00h

WELO ^ELO

NoTi: Preferred shapes for torsion 1.2,3,4,6,7,13 and 14

Fig. 8.6 Different Shapes of Stirrups

d) Use of Multi-Legged Stirrups — Multi-leg-
ged stirrups are required from the considera-
tion of shear stresses in the beam, or where
restraint against the buckling of bars in
compression is needed. The rules for stirrups
reinforcing steel in compression are the same
as those for columns. The vertical stirrups
may be provided as two-legged stirrups, four-
legged stirrups or six-legged stirrups at the
same section according to actual require-
ments {see Fig. 8.8). Open type stirrups as
shown in Fig. 8,9 may be used for beam-slab
construction where the width of rib is more
than 450 mm.

e) Stirrups in Edge Beams — Where designer
shows stirrups in any edge or spandrel
beam, these stirrups shall be closed and at
least one longitudinal bar shall be located
in each corner of the beam section, the size
of this bar is to be at least equal to the dia-
meter of the stirrup but not less than 12 mm.
These details shall be clearly indicated by
the designer. Typical cross-sectional details
are shown in Fig. 8.10 for normal and up-
turned edge or spandrel beams. For easier
placing of the longitudinal bars in the beam,
details for two-piece closed stirrups are
also shown. For the same reason, 90° stirrup
hook is preferred.

f) Minimum Reinforcement — Th& minimum
shear reinforcement in the form of stirrups
shall not be less than the following {see
Fig. 8.11).

tlNe OF POTENTIAL CRACK

8.7A REQUIREMENTS FOR BENT-UP BARS

Fig. 8.7 Bent-up Bars {Continued)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

193

SP : 34<S&T)-I987

•M- BARS AT SAME LEVEL

V 2 LE00EO CLOSED
STIRRUPS

BENT UP BARS
SECTION-AA

8.7B TYPICAL ARRANGEMENT OF BENT-'JP BARS AND VERTICAL STIRRUPS IN A CONTINUOUS BEAM

Fig. 8.7 Bent-Up Bars

8.8A

ir-^

) <

8.8B

8.8C

8.8D

THIS ARRANGEMENT
IN WHICH LINKS
OVERLAPS SHOULD BE
AVOIDED

Fig. 8.8 Examples of Miilti-Legged Stirrups

104

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

WTEflNAl LE6S
SHOUtO HOT
OVERLAP

O-ndfMAX.)

Fig. 8.9 Multi-Legged Open Type Stirrups
Cross-Section of a Broad Shallow
Beam with 6-Legged Stirrups

>l,v, Min =

0.4 6Sv

where

= total cross-sectional area of
stirrup legs effective in shear;

b = breadth of the beam or breadth
of the web of flanged beam; and

5v = stirrup spacing along the length
of the member;

/y = characteristic strength of the
stirrup reinforcement in N/mm^
which shall not be taken greater
than 415 N/mm^

However, in members of minor structural
importance such a^ lintels, or where the maxi-
mum shear stress calculated is less than
tne permissible value, this provision
need not be complied with.

g) Beafn of Varying Depth — E>etaii stirrup
sizes individually where beams have varying
depth. A ran^e of stirrup sizes nas to be
detailed {see Fig. 8.12 and also s.lU).

OPTrONAL

ALL STifmuPS IN EDGE
BEAM SHALL BE- CLOSED

CLOSED BY STANDARD 90
SriRftUP HOOKS eiTENSlON

Ip mt BARS CONTINUOUS
EXCEPT WHEN SPLICED TO
OTHER TOP STECL. THESE
BARS SHALL BE OF SAME
SIZE AS STIRRUPS IF STIRRUPS
ARE LARGER THAN 120

CORNER BARS SHALL BE PROPERUT
ANCHORED AT SUPPORTS

STIRRUPS AS CLOSED TIE

ONE TOP BAR PER
5TIRPUP AT l£AST
OF S/ME SIZE AS
STIf

STANDARD 9<P HOOK
EXTENSION • 12d

12f»MIN BARS CONTINUOUS
EXCEPT WHEN SPLICED TO
- OTHER TOP STEEL

^STANDARD 90 STIRRUP
HOOK EXTENSION- Cd

ORNER BARS SHALL BE
PROPERLY ANCHORED AT
SUPPORTS

STIRRUPS AND TOP BARS
FORM CLOSED TIE

120 MIN BARS CONTINUOUS
EXCEPT WHEN SPLICED 1$
OTHER TOP STEEL-
WHERE REQUIRED BY OESlBNER

rSTRAOHT BAR SPUCE;
LAP LENOTH SPECVIED
BY DESIGNER

CORNER BARS SHALL BE
PROPERLY ANCHORED AT
SUPPORTS

TWO-PIECE STIRRUPS FORM CLOSED T»E
AH dimmtioni in mfllimetret.

-CONSTRUCTION BREAK (IF RfiOUIRCD)

LcOIWCR

BARS SmUBf
___ .Y ANCHOMD AT
SUPPORTS

UPSTRANO BEAM

Fig. 8.10 Typical Details of Reinforcement in Edge and Spandrei Beam

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

105

SP : 34(}«tT)-I987

DESIGNED COMPRCSSION
STCEK;^ OOibO)

5t^ aL

MAX. SPACING OF STIRRUPS
>- DESIGNED TENSION STEEL

:^ 0-754

> 4$Q mm

. AMiy
^ 0-4 b

LONGITUDINAL SECTION

Hf»« ^

COVER TO
STIRRUPS IS

AtviAREAOF ^
STIRRUP
LEGS

SECTION- A A

COVER TO MAIN STEEL =
2SmmOR 1DIA.0FBAR(#)
WHICHEVER (S GREATER.

Fig. 8.11 Reinforcement Requirements for Beams

CONCERTINA STIRRUPS

m %

"sr

1 §

SECTION-AA

SIZE OF STIRRUPS TO
MAINTAIN SHAPE

ELEVATION

SECTION -BB

Fig. 8.12 Use of Concertina Stirrups in Beams of Varying Depth

h) Force not Applied to Top of Beam — Where
a load transfer is through the bottom or side
of a beam (for example, where one beam
frames into another), ensure that there is
sufficient suspension or hang-up reinforce-

ment at the junction in the main beam in the
form of stirrups to transfer the force to the
top of the beam. If the load is large, bent-up
bars may also be used in addition to
stirrups {see Fig. 8.13).

106

HANDBOOK ON CONCRETE REINFORCEMENT AM) DETAILING

SP : 34(S&T)-I«>«7

SECONDARY BEAM

MAIN BEAM

KNf UP HANSEK
TYPE iAitS

Fig. 8.13

8.4 Torsion Reinforcement — When a member
is designed for torsion, reinforcement for the same
shall be provided as follows {see Fig. 8.I4A):

a) The transverse reinforcement for torsion
shall be rectangular closed stirrups placed
perpendicular to the axis of the member.
The spacing of the stirrups shall not exceed
the least of xi, (xi +.Vi)/4 and 300 mm,
where xi and yi are respecively the short
and long dimensions of the stirrup. In a
beam with multi-legged stirrup, only the
stirrup going around the outer face shall
be considered to resist torsional force. In
members having a complex cross-section
(such as 1 and T-sections), each part (flanges,
ribs, webs, etc,) should contain closed
stirrups of its own {see Fig. 8.14B and C).

b) Longitudinal reinforcement shall be placed
as close as is practicable to the corners of
the cross-section and in all cases there shall
be at least one longitudinal bar in each
corner of the ties.

c) When the cross-sectional dimensions of the
members exceeds 450 mm, additional longi-
tudinal reinforcements shall be provided at
the side faces and the total area of such
reinforcement shall be not less than 0, 1
percent of the web area and shall be distri-
buted equally on two faces at a spacing not
exceeding 3()0 mm or web thickness which-
ever is lower.

8.5 Curtailment of Reinforcement — The extent
of curtailment of main reinforcement in beams
should be related to the bending moment diagram
subject to the conditions specified in Section 4.
However, simplified f urtailment rules illustrated in
Fig.^ 8.15, 8.16 ahd 8.17 may be used for
continuous beams, /simply supported beams and
cantilever beams, respectively under the following
circumstances:

a) the beams are designed for predominantly
uniformly distributed loads; and

b) in the case of continuous beams, the spans
are approximately equal (which do not
differ by more than 15 percent of the
longest).

SIOC FACE REWFOICC-
MEHT SRCOUIREO
WHEN DEPTH EXCEEDS '
iSOmmlOmRCCNTOF
VVEBAREADISTMSUTEO
EOUAUY ON TWO FACES)

STHHtUP TAKEM
ROUKD OUTCRMOST

l^ )00iiiiii

CORNER BARS

SHALL BE PROPERLY

ANCHORED AT SUPPORT

8.I4A SHEAR AND TORSION REINFORCEMENT IN
BEAMS

r — 1

i 7?

I w i I

8.I4B

8.I4C

Fig. 8.14 Sear and Torsion Reinforcement in
Rectangular and Flanged Beams

HANDBOOK ON CONCRETE I^INFORCEMENT AND DETAILING

107

SP:34(S&T)-1987

CLEAR SPAN

END SUPPORT

iRESTAINED)

« 0-15 li SHOULD NOT BE LESS THAN L4

INTERMEDIATE SUPPORT

NoTir: Applicable 10 continuous beams wiih approximately equal spans (not differing more than 15 percent)
and subjected to predominantly IJ.D.[.., and designed without compression steel.

Fig. 8.15 Simpliuhd CiiRiAiLMiNT Riiu-s for Continuois Beams

MINIMUM TWO BARS ^

f-|-50% L1OOV.

BRICK WALL SUPPORT

r n -»

*In case partially restraint members/ 35 percent of the- reinforcement shall also be provided for negative
moment at the support and fully anchored.

KKf. 8.16 SlMFLliniD Cl'RlAII.MHM RuLFS FOR SiMPLY SUPPORTED BeAM

25 Aft iMtti) SUBJECT TO MINIMUM
OF TWO BARS, ir NOT DCSIGNEO AS
A DOUBLY REINFORCED SECTION

8.17A CAMil.rVFR

Bi AM PROJFdlNC;
COl IJMN

? ROM A

Fig. 8.17 Simpfififd Ct:RiAiLMHNr Rt lfs

A CaMUFYFR \h-..\M (G)niinuc(f)'*

FOR

8.6 Edge and Spandrel Beam — T-beams or L-
beams are usually designed as internal and
external beanns supporting a floor slab; where
part of the slab form the horizontal portions of
the 1- or L-beani.

Where the reinforcement of a slab which is
considered as the flange of T- or L-beam, is
parallel to the beam, transverse reinforcement
extending to the lengths indicated in Fig. 8.18
shall be pro\ided. if the quantity of such
transverse reinforcement is not specially
determined by calculations it shall not be less than
60 percent of main reinforcement in the centre of
the span of slab constituting the flange.

8.7 Corners and Cranked Beams - Recommen-
dationsfor various methods of reinforcing corners
are giving herein based on reference 6. It is to be
noted that closing corners present no major.

108

liANDBOOK ON ( ONC RFTK HKINFORCKMKM AND DETAILING

0-25 Aft (MIR) SUBJECT
TO MINIMUM TWO BARS

SP : 34(S&T>-1987

BARS TO HAVE
THE REQUIRED
ANCHORAGE
VALUE ON
BOTH SIDES.

8 I7B CANTILEVER BEAM PROJECTING FROM A BEAM OVER A COLUMN

Fig. 8.17 Simplified Curtailment Rules for a Cantilever Beam

^IM

iLAA

^ IM

; • • • • *^

rf .'. •

SECTION XX

Fig. 8.18 Transverse Reinforcement in Flange of T-Beam when Main Reinforce-
ment OF Slab is Parallel to Beam

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

109

SP : 34(S&T).!987

problem, but opening corners require careful
detaiijag (see Fig. 8.19 and Fig. 8.20).

RESULTANT TENSILE
FORCE ACROSS
CORNER

■\

lizJ

Fig, 8.19 Opening Corner

Fig. 8,22 Hairpin with Splay Reinforcement

8.7.2 W -Opening Corners With More Than I
Percent Reinforcement — If the area of reinforce-
ment exceeds one percent, provide transverse steel
as well as splay steel as in Fig. 8,23. (The use of a
splay is also strongly recommended.)

RESULTANT
COMPRESSIVE
FORCE ACROSS
CORNER

Fig. 8.20 Closing Corner

8.7,1 90°'Opening Corners With J Percent
Reinforcement or Less — ^hcre the amount of
reinforcement in the beam is equal to or less than
1 percent, detail the reinforcement as shown in
Fig. 8.21 or Fig. 8.22, the splay steel being equal
to 50 percent of the main steel.

BARS

Fig. 8.23

8.7.3 Cranked Beams — The recommended
methods of detailing are shown in Fig. 8.24, 8.25
and 8.26.

U-BARS

ADDITIONAL BAR

Fig. 8.24

Fig. 8.21

Fig. 8.25

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNG

SP : 34<S&T)-I987

Fig- 8.26

8.7.4 Beam and Column Junction — Where a
coiumn extends above a beam, bend the beam top
reinforcement down into the column but if it is
necessary to bend the bars up, detail additional
steel as in Fig, 8.27.

Fig. 8.27

8,7.5 Closing Corners — At closing corners
provide adequate radii (equal to at least 7=5 bar
diameters) and some additional reinforcement as
in Fig. 8.28.

8.8 Beam of Different Depths - Typical
arrangements of reinforcement over the support
when the beam on either side of the support are of
different depths is shown in Fig. 8.29.

8.9 Tie Members — As a tie is under pure
tension there is no tendency to burst like an
axiaily loaded column and therefore binders are
not required. But, in order to form the
longitudinal bars into a cage, a minimum number
of links is used. As there is theoretically no shear
or bending moment acting on a tie, only main
longitudinal reinforcement is required. The main

8.9.1 End Details — These shall provide
adequate anchors and correct bond lengths. In

EXTRA U-BARS

EXTRA
U-BARS

Fig. 8.28

Fig. 8.29 Beams at Different Depths

consideration is the end conditions where a
method should be devised to anchor the tie
and /or spread its axial load into the connecting
members.

practice a small splay at the ends of the tie is
made to allow for any slight moment that may be
induced at the ends. Simple end details for fight
loading are shown in Fig. 8.30. The ties are shown
by the arrows.

HANDBOOK ON CONCRFTE REINFORCEMENT AND DETAILING

SP : 34(S&T)-19S7

NOMIMAL LINKS

^«

8.30 A

ANCHOR SPLICi
(SURTFR SARS)

8.30B

.30C 8.30D<

Fig. 8.30 Tie End Connections for Light Loading

112

TI\NOBOOK ON CONCRETE REINFORCEMENT AND DCTAIUNG

SP : 34(S&T)-1987

For heavier axial loading, the ends shall be
more splayed out to distribute • the load
adequately. Typical details are shown in Fig. 8.31.

In Fig. 8.31 (A and B) it will be seen that as the
splay is increased in size, the embedded and hence
bond length of the main tie bars is also increased.

In Fig. 8.3 IC extra links or hoops shall be
provided as shown to resist the tendency of the
large loop to burst under axial load. In Fig. 8.31
the main bars have been shown with double lines
for clarity. When detailing they would be shown
thick lines in the norma! way.

8.3IC

Fig. 8.31 Tie End Connections for High Loading

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-!987

8.10 Haunched Beams — In very heavily loaded
beams, for example a warehouse structure, the
shear stress and negative bending moment at the
supports will be high. An economical method of
overcoming this problems is to provide the beams
with haunches as shown in Fig. 8.32. There are no
rules governing the size of haunches, but those
shown in Fig. 8.32 are considered ideal.

8.10,1 Main Reinforcement in haunches —
Figure 8,33 shows the typical main tensile

reinforcement in an end external haunch. The
main bars are carried through the haunch as if it
did not exist, with pairs of bars a, 6, c, etc,
stopped off in accordance with a cut-off bending
moment diagram. Bars h are placed parallel to the
haunch to carry vertical links (omitted in the
figure for clarity).

A similar method of reinforcing to that shown
in Fig. 8.33 can also be used for internal
haunches. This is shown in Fig. 8.34.

Tip;

BETWEEN

L/10 & L/8 SLOPE 1:3 JM ^

HAUNCH

Fig. 8.32 Beam Haunches

Fig. 8.33 Main Reinforcement in End Haunches {See Fig. 8.33 for Section xx)

Fig. 8.34 Main Reinforcement in Haunches {See Fig. 8.37 for Section xx)

"4 HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-19«7

8.10.2 Stirrups in Haunches ~- The stirrups in
haunches can either be positioned normally to
the haunch as shown in Fig. 8.35A, or placed
vertically as in Fig. 8J5B. Most designers prefer
method shown in Fig. 8.35B.

LINK PLACED
NORMAL TO HAUNCH

X.35A

VERTICAL
LINKS

8.35B

Fig. 8.35 Links or Ties in Halnchs

If in Fig. 8.33 and 8.34, the h bars were placed
near the outside edge of the beam they would foul
the outside main horizontal bars. They should,
therefore, be placed on the inside as shown in
Fig. 8.36 so that two different sets of stirrups are
required throughout the whole length of the
haunch {see 8.10).

8.11 Beam of Varying Depth — Stirrups need to
be detailed individually wherever beams have
varying depths and a range of stirrup sizes have to
be adopted.

8.11.1 The different stirrup sizes may be
reduced in number by using concertina stirrups
(see Fig. 8.12) with the legs lapped with tension
lap length. The difference between the lengths of
successive groups should be at least 50 mm. In
order to maintain the correct size of the member,
use closed stirrups at centre-to-centre distances of
at least 1000 mm. Ensure that concertina stirrups
are properly tied and maintained in position
during concreting.

-■

h h
■ 1

SECTION X-X

Fig. 8.36 Haunch Links

S.t2 Intersection of Beams

8.12.1 General ~ Ensure that, at beam-beam
intersections, reinforcement is so arranged that
layers in mutually perpendicular beams are at
different levels.

8.12.2 Top Steel — It is good practice, for the
following reasons, to pass the secondary beam
steel over the nfain beam steel:

a) secondary beam steel is usually of smaller
diameter and requires less cover, and

b) secondary beam top reinforcement is
available to act as a support for the slab top

reinforcement.

Where the main beam is very heavily stressed,
however, it may be more economical to pass the
main beam steel over the secondary

reinforcement.

8.12.3 Bottom Steel — To accommodate
bottom bars, it is good practice to make
secondary beams shallower than main beams,
even if by only 50 mm (see Fig. 8.37). Where
beam soffits are at the same leveX the secondary
beam steel should pass over the main beam steel.
Unless the secondary beam span is short, bars of
diameter less than 25 mm be draped (see
Fig. 8.38). Cranking of bottom bars is usually not
necessary.

If it is required that the beam cages be pre-
assembled, provide splice bars 7.6).

8.13 Openings in the Web ~ Adjacent openings
for services in the web of flexural members shall
be arranged so that no potential failure planes,
passing through several openings, can develop. In
considering this, the possible reversal of shear

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

115

SP : 34(S&T)-I987

Secondary beam

Main
beam

Fig. 8.37

Fig. 8.38

Draped mam bar
(Tie to side of stirrup)

force, associated with the development of the
flexural overstrength of the members, should be
taken into account.

8.13.1 Small square or circular openings may
be ptaced in the mid-depth of the web provided
that cover requirements to longitudinal and
transverse reinforcement are satisfied, and the
clear distance between such openings, measured
along the member, is npt less than 150 mm. The
area of small openings shall not exceed I 000 mm^
for members with an effective depth, c/, less than
or equal to 500 mm, or 0.004 ^2 vvhen the
effective depth is more than 500 mm.

Note — Small openings with areas not exceeding those
specified in 8.13.1 are considered not to interfere with the
development of the strength of the member. However, such
openings must not encroach into the flexural compression
zone of the member. Therefore, the edge of a small opening
should be no closer than 0.33 d, to the compression face of
the member, as required byr<l.l2.3. When two or more small
openings are placed transversely in the web, the distance
between the outermost edges of the small openings should
be considered as being equivalent to the height of one large
opening and the member should be designed accordingly.

8.13.2 Webs with openings larger than that
permitted by 1 8.12.1 shall be subject to rational
design to ensure that the forces and moments are
adequately transferred in the vicinity of the
openings. This will require the design of
orthogonal or diagonal reinforcement around
such openings.

8.13.3. Whenever the largest dimension of an
opening exceed one-quarter of the effective depth
of the member, it is to be considered large. Such
openings shall not be placed in the web where
they could affect the flexural or shear capacity of
the member, nor where the total shear stress
exceed 0.36 \//^, or in potential plastic hinge
zones. In no case shall the height of the opening
exceed 0.4 d nor shall its edge be closer than
0.33 d to the compression face of the member to

ensure that the moments and shear forces can be
effectively transmitted by the compression zone of
the member.

8.13.4 For openings defined by 8.13.3,
longitudinal and transverse reinforcement shall be
placed in the compression side of the web to resist
one and one-half times the shear across the
opening. Shear transfer in the tension side of the
web shall be neglected.

Note — Only the part of the web above or below an
opening which is in compression should be considered tc
transmit shear. The stiffness of the tension part is conside-
red to be negligible because of extensive cracking. The
amount, location and anchorage of the longitudinal rein-
forcement in the compression part of the web above the
opening must be determined from first principles so as to
resist one and one-half times the moment induced by the
shear force across the opening. Similarly shear reinforce-
ment in the compression chord adjacent to the opening must
resist 150 percent of the design shear force. This is to ensure
that no failure occurs as a result of the local weakening of
the member due to the opening. Effective diagonal rein-
forcement above or below the opening, resisting one and
one-half times the shear and moment, is also acceptable.

8.13.5 Transverse web reinforcement,
extendmg over the full depth of the web, shall be
placed adjacent to both sides of a large opening
over a distance not exceeding one-half of the
effective depth of the member to resist twice the
entire design shear across the opening.

Note — At either side of an opening where the moments
and shear forces are introduced to the full section of a beam,
horizontal splitting or diagonal tension cracks are to be
expected. To control these cracks, transverse reinforcement
resisting at least twice the design shear force, must be
provided on both sides of the opening. Such stirrups can
be distributed over a length not exceeding 0.5 d at either
side immediately adjacent to the opening.

8.13.6 A typical detail of reinforcement
around a large opening in the web of a beam,
complying with the above requirements, are
Shown in Fig. 8.39.

116

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

sp : SMStaytfn

rSTIRRUPS TO RESIST V5 Vu

FLEXURAL STEEL TO

RESIST MOMENT VStOSl^Vu)

STIRRUPS TO
RESIST ?Vu

NOMINAL STIRRUFS

Fio. 8.39 Details of Requirements at a Large Opening in the Web of a Beam

HANDWMK ON CONOtm HINFOIICEMENT AND DCTAIUNC

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 9
Floor Slabs

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34<S&T)-1987

SECTION 9
FLOOR SLABS

9.0 Solid Slabs — The requirements specified in

9.1 to 9.7.2.2 apply to solid slabs other than flat
slabs.

9.1 Minimum Reinforcement — In solid
reinforced concrete slabs* the reinforcement in
either direction expressed as a percentage of the
gross-sectional area of the concrete shall not be
less than:

a) 0.15 percent where plain bars are used, and

b) 0.12 percent where high yield strength (hot
rolled and cold twisted) deformed bars or
welded wire fabric are used.

9.2 Spacing, Cover and Diameter

9.2.1 Spacing

a) The pitch of the bars for main tensile rein-
forcement in solid slab shall be not more
than thrice the effective depth of such slab
or 450 mm, whichever is smaller.

b) The pitch of the distribution bars or the
pitch of the bars provided against shrinkage
and temperature shall not be more than 5
times the effective depth of such slab or
450 mm, whichever is smaller. Table C-6
(see Appendix C) give area of bars for
different spacing and diameter of bars.

9.2.2 Cover

a) The cover at each end of reinforcing bar
shall be neither less than 25 mm nor less
than tw'ce the diameter of such bar.

b) The minimum cover to reinforcement (ten-
sion, compression, shear) shall be not less
than 15 mm, nor less than the diameter of
bar.

9.2.3 Bar Diameters — The main bars in the
slab shall not be less than 8 mm (high yield
strength bars) or 10 mm (plain bars) and
distribution steel shall not be less than 6 mm
diameter bars. The diameter of the bar shall not
also be more than one-eighth of the slab
thickness.

9.3 Simply Supported Slabs

9.3.1 Slabs Spanning in One Direction — A
slab that is supported on two opposite sides only
by either walls or beams is said to be spanning in
one direction. The slab is considered as spanning
in one direction even when the slab is supported
on all four sides if the effective length of the slab
exceeds two times its effective width. The shorter
span is to be considered for design.

Figure 9.1 shows the general details of slab
spanning in one direction. It clearly indicates the
size and thickness of the slab and reinforcement,
the cover and the spacing. Slab thickness shall be
indicated both in plan and section. Where series
of identical bars are used, it is customary to show
only one bar. The bars in the shorter direction
(main bars) are placed in the bottom layer. At
least 50 percent of main reinforcement provided
at mid span should extend to the supports. The
remaining 50 percent should extend to within 0.1 /
of the support.

The bars in longer direction of the slab are
called distribution or transverse steel. These assist
in distribution of the stresses caused by the
superimposed loading, temperature changes and
shrinkage during the hardening process. These
bars are placed in the upper layer and tied with
the main steel bars to keep them in correct
position during concreting.

9.3.2 Slabs Spanning in Two Directions — A
simple slab spanning in two directions {lyjk ^ 2)
and supported on four brick walls is shown in
Fig. 9.2.

As the slab is spanning in both directions the
reinforcement in each direction shall be
considered as main reinforcement. The bars in the
shorter direction are generally placed in the
bottom layer and tied with the bars in the longer
direction placed above at suitable intervals to
keep their relative positions intact during
concreting.

At least 50 percent of the tension reinforcement
provided at mid-span should extend to the
supports. The remaining 50 percent should extend
to within 0.1 h or 0.1 /y of the support, as
appropriate, where U and /y are effective spans in
the shorter direction and longer direction,
respectively.

9.4 Restrained Slabs — When the corners of a
slab are prevented from lifting, the following
simplified detailing rules may be applied,
provided the slab is designed for predominantly
uniformly distributed loads.

Note 1 — The analysis of uniformly distributed load and
concentrated loads may be done separately, and with
appropriate theories. The reinforcement quantities deter-
mined in this way should be superimposed.

Note 2 - If an end support is assumed to be a free support
in the analysis, but if the character of the structure is such
that restraint may nevertheless occur at the support, a
restraint moment equal to half the mid-span moment in the
strip concerned may be adopted.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

121

DtSTRIBUTION BARS
(SEE NOTE 2)

SECTION -BB

MAIN BARS (SEE NOTE 1)

■^^

•—

DETAILS OF MAIN BARS AlOHC

THIS LINE

SPECIFY THICKNESS
IN PLAN

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STRIBUT
NtMUM 2

<
<

oS .

•
Z

!— ' !2

U ■-

1^^

•IB

PLAN

Note 1 — Diameter < 8 mm for deformed bars; 10 mm for plain bars; Spacing > 3d or 450 mm
Note 2 — Diameter < 6 mm; Spacing > 5d or 450 mm

Fig. 9.1 Typical Details of a Slab Spanning in One Direction

!«:
o

o
»

SB
93

H
Z

o
o

H
>

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z

(/I

CD
CD

< hi

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Li^

COVE R
15CM.(MIN.)

Oil

BARS IN SHORTER DIRECTION SHAU
BE PLACED BELOW BARS PLACED IN
THE LONGER DIRECTION

SPECJFY THICKNESS
IN PLAN

DETAIL OF BARS IN SHORTER DIRECTION

U-

PLAN

0*5 Ast >/- DISTRIBUTION BARS (2 BARS HIN.)

fe:

■ I I

SECTION-AA

Fig. 9.2 Typical Details of a Slab Spanning in Two Directions

SP : 34(S^cT)-1987

9.4.1 The slabs are considered as divided in
each direction into middle strips and edge strips
as shown in Fig. 9.3, the middle strip being three-
quarters of the width and each edge strip one-
eighth of the width.

9.4.2 The tension reinforcement provided at
mid-span in the middle strip shall extend in the
lower part of the slab to within 0.25 / x>f a
continuous edge, or 0.15 / of a discontinuous
edge.

9.4.3 Over the continuous edges of a middle
strip, the tension reinforcement shall extend in the
upper pant of the slab a distance of 0.15 /from the
support, and at least 50 percent shall extend a
distance of 0.30/.

9.4.4 At a discontinuous edge, negative
moments may arise. They depend on the fixity at
the ledge of the slab but, in general, tension
reinforcement equal to 50 percent of that
provided at mid-span extending O.I /into the span
will be sufficient.

9.5 Cantilever Slabs — The main reinforcement
shall be placed in the top of cantilever slab
extending to sufficient length over^the support
and back into the normal span.THe method of
curtailment shall conform to the requirements
specified in Section 4.

Support to the top steel of cantilever slabs at
spacing (for stools and chairs) should preferably
be specified in the detailing drawing. The bending
of the main bars should be such that they
contribute to the supporting of the steel, that is,
bars that extend to the end should have vertical
bends, with a fixing bar at the bend.

The secondary steel at right angles to the
support may be designed and detailed to carry
construction loading in the propped condition, if
necessary.

The deflection in cantilever slabs can be
reduced by the addition of compression steel at
the bottom. This would also be helpful in
counteracting possible reversal of bending
moments.

9.4.5 Reinforcement in edge strip parallel to 9.5.1 The simplified curtailment rules

the edge, shall comply with the minimum illustrated in Fig. 9.7 may be used for cantilever

reinforcement requirement (9.1) and the slabs when they are designed for predominantly

requirements for torsion in 9.4.6. to 9.4.6.2. uniformly distributed loads.

9.4.6 Torsional Reinforcement — Torsional
reinforcement shall be provided at any corner
where the slab is simply supported on both edges
meeting at that corner and is prevented from
lifting unless the consequences of cracking are
negligible. It shall consist of top and bottom
reinforcemem, each with layer of bars placed
parallel to the sides of the slab and extending
from the edges a minimum distance of one-fifth of
the shorter span. The area of reinforcement per
unit width in each of these four layers shall be
three-quarters of the area required for the
maximum mid-span moment per unit width in the
slab (see Fig. 9„4A).

9.4.6.1 Torsional reinforcement equal to
half that described in 9.4.6 shall be provided at a
corner cointained by edges over only one of which
the slab is continuous, (see Fig. 9.4B.)

9.4.6.2 Torsional reinforcement need not be
provided at any corner contained by edges over
both of which the slab is continuous.

9.4.7 A slab shall be treated as spanning one
way (in the shorter direction) when ratio of
effective span in the longer direction to the
effective span in the shorter direction is greater
than 2.

9.4.8 Figure 9.5 illustrates curtailment of bars
in a restrained slab spanning in two directions
based on the above rules using straight bars or
bent-up bars.

9.4.9 Re-entrant Corners — Diagonal rein-
forcemeniL shall be placed at all re-entrant corners
to keep crack widths within limits (see Fig. 9.6).

9.5.2 Tie Backs and Counter Masses to
Cantilevers

9.5.2.1 Cantilever at the bottom of
beams — Ensure, when a cantilever is at the
bottom of a beam, the design of the stirrups in the
beam provides for moment, shear, hanging
tension and, if necessary, torsion. If possible,
provide in the detailing of this steel for placing of
the beam steel without the necessity of the
threading of the main beam steel through the
cantilever anchorage loops. The details should
conform to the basic principles applicable to
opening corner in retaining walls and the beams.
Figure 9.8 provides three alternative niethods of
anchoring bars in supporting beams.

Note — Note the special difficulty induced by bent-up
bars in the beam steet:

a) Curtailed bars going to the back of a beam may drift
out of position during casting of concrete.

b) Hairpin type bars should be related to the horizontal
stirrup spacing, and this may cause difficulties.

c) Loo|)s of 270° are difficult to bend and place in
position.

9.5.2.2 Cantilever at the top of bedms —
Where the weathering course is 30 mm or less,
crank the bars at a slope not exceeding 1 in 6 \see
Fig. 9.9(A)]. Ensure that the combination of top
bars and stirrups is such as to provide the
required restraint. Note that if a bar is laced over
and under the beam bars, it is fully restrained
provided that the beam top bars are heavy enough
and a stirrup is within 50 mm of such ban. If the
bar is not so laced, detail the steel to ensure the
anchorage against bursting {see Fig. 9.9).

124

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

n
z

DIRECTION OF REINFORCEMENT

Fig. 9.3 Slab Spanning in Two Directions— Arrangement of Strips and Direction
OF Reinforcement

so
00

■-a

SP : 34<S&T)-1987

1
1

_[. ..... -^

•

" ' 1 A« (T t B)

•~

•"

, I

. 1

4 A«- IT D1 1

7*^5 II « D/

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Ix • SHORTER SPAN

9.4A Corner with Two Discontinuous Ends

CO
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1 \

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9.4B Corner with One Discontinuous Ends

Fig. 9.4 Torsional Reinforcement in Slabs

126

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

0-31

EDGE BEAM

INTERMEDIATE BEAM

B- USING STRAIGHT BARS

Fig. 9.5 Simplified Rules for Curtailment of Bars— Section Through Middle Strip

SP ; 34(S& r)-1987
WAIL SUPPORT

SLAB

-AODITtONAL DIAGONAL BARS
(TOP t BOTTOM)

SLAB

ADDITIONAL DIAGONAL
BARS ( TOP t BOTTOM)

BEAM SUPPORT

Fig. 9.6 Additional Reinforcement at Re-
entrant Corners

9.5.3 Cantilevers Around Corners — Ensure
that, in a corner of a cantilever slab, the detailing
is such that tie-back loading and the deflections
that arise from this are accounted for. Avoid *fan'
type detailing. Take particular care with drainage
inlets.

9.6 Openings in Slab: -- Special detailing for
openings for lift shafts, large service ducts, etc, in
the floors shall be given in the drawing. Such
openings shall be strengthened by special beams
or additional reinforcement around the openings.
Due regard shall be paid to the possibility of
diagonal cracks developing at the corners of the
openings.

Note — The number, size and position of trimming bars
is a function of the design, and should be determined by the
designer.

9.6.1 Where openings are small and the slab is
not subjected to any special type loading or
vibration conditions, the following general
detailing rules may be followed around openings
{see Fig. 9.10 and 9.11):

a) At least one half the quantity of principal
steel intersected by the opening is to be
placed parallel to principal steel on each side
of the opening extending L^ beyond the
edges of the opening.

b) Diagonal stitching bars are put across the
corners of rectangular holes or so placed as

to frame circular openings. They should be
placed both at top and bottom if the thick-
ness of slab exceeds 150 mm.- The diameter
of these bars should be the same as that of,
the larger of the slab bars, and their length
should be about 80 diameters.

Note — In general openings of diameter less than 250 mm
or of size smaller than 200 X 200 mm may be treated as
insignificant openings.

9.7 Slabs with Welded Wire Fabric

9.7.1 General — Welded wire fabric is either
oblong mesh or square mesh arid is supplied in
either rolls or flat sheets. The details regarding
material, types and designation, dimensions, sizes
of sheets or rolls, weight, tolerance, mechanical
properties, etc, are all covered in IS: 1566-1982
'Specification for hard-drawn steel wire fabric for
concrete reinforcement {second revision) ' {see also
Section I).

9.7.2 Detailing

9.7.2.1 To ensure that correct size of fabric
is laid in right direction, small sketches should be
inserted on the plan to indicate the direction of
span of the fabric. Details at A and B in Fig. 9.12
indicate square and oblong welded wire fabric,
respectively, in plan view of slab.

9.7.2.2 The actual position of the welded
wire fabric sheet in slab panels may be shown by a
diagonal line together with the description of the
mesh used. Bottom sheets should be shown with
diagonal drawn from bottom left-hand corner to
the top right-hand corner. Top sheets should be
shown from top left-hand corner to the bottom
right-hand corner. A schedule may also be
included in the structural drawing indicating the
mesh sizes, length and width, and cutting details
for welded wire fabric sheets for different slabs
panels. A typical plan is illustrated in Fig. 9.13
{see Section 5 for schedule),

9.8 Flat Slabs

9.8.1 General— J\{t term flat slab means a
reinforced concrete slab with or without drops,
supported generally without beams, by columns
with or without flared column heads {see Fig.
9.14). A flat slab may be solid slab or may have
recesses formed on the soffit so that the soffit
comprises a series of ribs (waffles) in two
directions. The recesses may be formed by
removable or permanent filler blocks.

9.8.1.1 {see Fig. 9.15)

a) Column strip — Column strip means a
design strip having a width of 0.25 h^ but
not greater than 0.25 U on each side of the
column centre line, where h is the span in
the direction moments are being determined,
measured centre-to-centre of supports and h
is the span transverse to /], measured centre-
to-centre of supports.

128

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

i^i

GREATER OF
0-51 OR L(i

STEEL SUPPOhTING
CHAIRS NEAR SUPPORT

rTOP DISTRIBUTION STEEL
TIED TO MAIN STEEL

0-5 A,t

' A '"-^ '-'

BRICK WALL

STANDARD BEND

AT 90'' IF REQUIRED

TO ACT AS A CHAIR ALSO

BOTTOM STEEL ( IF REQUIRED TO '
REDUCE DEFLECTION AND TO
RESIST REVERSAL OF BENDING
MOMENT )

9.7A CANTILEVER SLAB CONTINUOUS OVER A BRICK WALL

BEAM DESIGNED FOR
TORSIONAL BEHblHG
MOMENT

7S(MIN.)

*>,7BSlAB CANr!i.;:VERlNC FRO^

>-; ("5 T ^~- :,>.'

LEVf!>

SP : 34(S&T)-I987

(

f— 1

LCANTILEVER

CAMTItEVeR-l 9 4A

.CANTILEVER
9.4B

V7Z

CHAIRS NEAR
SUPPORTS

9.4C

ADDITIONAL REINFORCING BARS

Fig. 9.10 Additional Reinforcement Around
A Rectangular a Opening in a Slab

Note — Bottom bars left out for clarity

Fig. 9.8 Cantilever Slabs at the Bottom of

Beams

SLOPE f 1IN (

CANTLEVER
t •10

•OO 9.9 A

I »1 \fS^[=^

CANTILEVER
30 < S < ISO

^4/3 (MIN.)

9.9B

CHAIRS AT SUPPORT

ADDITIONAL REINFORCING BARS

Fig. 9.11 Additional Reinforcement Around
A Circulor Opening in a Slab

CANTILEVER

t > 110

ULL TSttSraN
LAP PROM HERS

9.9C

♦ m

Note ~ Bottom bars left out for clarity

Fig. 9.9 Cantilever at the Top of Beams

A B

Fig. 9.12 Welded Wire Fabric in Plan View of
Slab.

130

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

■'— r-^1-— ^ — 1

2M0

!7— r

15 mm
COVER

SECTION XX

-N— »J^

5=*

t- 2740

Fig. 9.13 Plan Showing Typical Details of Welded Wire Fabric

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

131

SP : 34(S&T).1987

CRITICAL SECTION
FOR SHEAR-

CRITICAL SECTION FOR
.SHEAR ADJACENT TO
DROP

CRITICAL SECTION POO
SHEAR tMMCI»AT€LY
ADJACENT TO COLUMN^

11A SLAB WITHOUT DROP t COLUMM
WITHOUT COLUMN HEAO

■CRITICAL SECTION
FOR SHEAR

11 B SLAB WITH DROP ft COLUMN
WITH COLUMN HEAD

ANY CONCRETE IN THIS AREA
TO BE NEGLECTEO IN THE
CALCULATIONS

.110 SLAB WITHOUT DROP % COLUMN
WITH COLUMN HEAD

Note — De is the diameter of column or column head lo be considered for des\gn and d is effective
depth of slab or drop as appropriate.

Fig. 9.14 Critical sections for Shear in Flat Slabs

b) Middle strip — Middle strip means a design
strip bounded on each of its opposite sides
by the column strip.

c) Panel — Panel means that part of a slab
bounded on each of Us four sides by the
centre line of a column or centre line of
adjacent spans.

9.8.2 Proportioning

9.8.2.1 The minimum thickness of slab shall
be 125 mm.

9.8.2.2 Drops ~ The drops, when provided,
shall be rectangular in plan and have a length in
each direction not less than one-third of the panel
length in that direction. For exterior panels, the
width of drops at right angles to the non-
continuous edge and measured from the centre
line of the columns shall be equal \to one-half the
width of drop for interior panels.

9.8.2.3 Column heads — Where column
heads are provided, that portion of a column head
which lies within the largest right circular cone or
pyramid that has a vertex angle of 90° and can be
included entirely within the outlines of the column
and the column head, shall be considered for
design purposes {see 9.13).

9.8.3 Slab Reinforcement

9.8.3.1 Spacing — The spacing of bars in a
flat slab shall not exceed twice the slab thickness,
except where a slab is of cellular or ribbed
construction.

9.8.3.2 Area of reinforcement — When drop
panels are used, the thickness of drop panel for
determination of area of reinforcement shall be
the lesser of the following:

a) Thickness of drop, and

b) Thickness of slab plus one-quarter the dis-
tance between edge of drop and edge of
capital.

9,8.3.3 Minimum length of reinforcement

a) Reinforcement in flat slabs shall have the
minimum lengths specified in Fig. 9.16.
Larger lengths of reinforcement shall be
provided when required by analysis.

b) Where adjacent spans are unequal, the
extension of negative reinforcement beyond
each face of the common column shall be
based on the longer span.

132

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

COLUMN STRIP

Fig. 9.15 Panels, Column Strips and Middle Strips

9.8.3.4 Anchoring reinforcement

a) All slab reinforcement perpendicular to a
discontinuous edge shall have an anchorage
(straight, bent or otherwise anchored) past
the internal face of the spandrel beam, wall
or column of an amount:

\) for positive reinforcement — not less
than 15 cm except that with fabric rein-
forcement having a fully welded trans-
verse wire pirectly over the support, it
shall be permissible to reduce this length
to one-half of the width of the support or
5 cm, whichever is greater; and

2) for negative reinforcement — such that
the design stress is developed at the inter-
nal face, in accordance with Section 4.

b) Where the slab is not supported by a span-
drel beam or wall, or where the slab canti-
levers beyond the support, the anchorage
shall be obtained within the slab.

9.8.3.5 When the design is based on the
direct design method specified in IS : 456-1978,
simplified detailing rules as specified in Fig. 9.17
may be followed. A typical arrangement of bars in
a flat slab with drop panels is shown in Fig. 9.17.

9.8.4 Openings in Fiat Slabs — Openings of
any size may be provided in the flat slab if it is
shown by analysis that the requirements of
strength and serviceability are met. However, for
openings conforming to the following, no special
analysis is required (see also 9.6):

a) Openings of any size may be placed within
the middle half of the span in each direction,
provided the total amount of reinforcement
required for the panel without the opening is
maintained.

b) In the area common to two column strips,
not more than one-eighth of the width of strip
in either span shall be interrupted by the
openings. The equivalent of reinforcement

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

133

SP : 34(S&T)-1987

HINIHUH
PERCENTAGE
OF STEEL
AT SECTION

REMAINDER

50
REMAINDER

too

WITHOUT DROP PAHEl

WITH DROP PANEL

/_^ r-«-::H — I I — 1/

75 mm max.

1 50 mm

•I \y 1

0.1?5^ max,

*- ^24 BAR DIA OR

300 mm min. ALL BARS

150 mm min.

^^-<~">^

0-125 t max, — ^ - -*.4-^-U-24 I
75 mm max, — 'f ■*;;^_/. ^t"*

r'*/

■^'

^^^

EDGE OF
DROP

BAR DtA OR
300 mm min.

—-,z.

-/-

EDGE OF
DROP

U-C^

(NO SLAB CONTINUITY)

(CONTINUITY PROVOEO) (NO SLAB CONTINUE Y |

— ■ — - — "— ~(

Bar Length from Facb of Support

Minimum Length

Maximum length

Mark

Length

014/.

0-20 /,

022 /,

30/,

0-33 /,

0-20 /.

0-24 /,

Bent ban at exterior tupporu may be used IT a general analysis is made.

Noi* — i> IS the diameter of the column and the dimension of the rectangular column in the
direction under coiutderation.

134

Fig. 9.16

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

COLUMN CAP

DROP PA

SECTION THROUGH MIDDLE STRIP

Fig. 9.17 Typical Ajirangement of Bars in a Flat Slab with Drop Panels

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

135

SP : 34(S&T)-1987

interrupted shall be added on all sides of the
openings.

c) In the area common to one column strip and
one middle strip, not more than one-quarter
of the reinforcement in either strip shall be
interrupted by the openings. The equivalent
of reinforcement interrupted shall be added
on all sides of the openings.

9.8.5 Shear Reinforcement at Column Heads
and Dropped Panels — The best method of provi-
ding shear reinforcement for slabs at column
heads is to use beam cages in one direction and
bars in the other direction laid under and on top
of the steel in the cages {see Fig. 9.18). Other
methods such as the following may also be used
depending upon their suitability:

a) Half or open stirrups suspended from the
top steel;

b) Use of serpentine bars {see Fig. 9.19A).

c) Spiders made of bent bars (for deep slabs)
{see Fig. 9.I9B).

d) Structural steel frames made of plate.

A few more methods of detailing shear
reinforcement in flat slabs are given irr Fig. 9.20 to
9.22.

9.9 Waffle Slabs

9.9.1 Definition — A waffle flat slab is a two-
way joist system. The two-way joist portion may
be combined with a solid column head or with
solid wide beam sections on the column centre
lines for uniform depth construction.

9.9.2 Size of Waffles — Re-usable forms of
standard size shall be used for economy. These
shall provide the width of rib at least 10 cm and
spaced not more than 100 cm clear, and depth not
more than 3'/^ times the minimum width.
Standard size may be adopted for these moulds as
50 X 50 cm, 60 X 60 cm, 80 X 80 cm, and 100 X
100 cm and depth as 15, 20, 25, 30, 35, 40, 45,
and 50 cm.

9.9.3 Detailing of Reinforcement in the
Waffle Slab (With Solid Head and Square
Interior Panel) — Ensure that at least 50 percent
of the total main tension steel in the ribs is carried
through at the bottom on to the support and
anchored {see Fig. 9.23).

136

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP:34(S&r)-1987

SECTION A-A

a=^

COVER

STiftRUPS

TOP STEEL

t ^ COVER

STIRRUP

BOTTOM
STEEL

SECTION B-B

Fig. 9J8 Shear Reinforcement for Slab at Column Heads

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

137

SP : 34(S&T)-1987

1 1

! !

I" fWU 1

--»--

/W j N I

9.19A 9.I9B

Fig. 9.19 Examples of Shear Reinforcement for Slabs at Column Heads

COLUMN

rLINKS FIXED TO SAME
LEVELS OF REINFORCEMENT

PROVIDE FIXING BARS
WHERE MAIN BARS ARE
NOT PRESENT

SECTION -AA
I II 1*1114

I i 4 I I I •*

I I I I

1 - -

4 + ^ ^ ^ ^ J- i
f t » f I f

jy- LINKS (TYP.)

*• A

■f t t I I f » t ■ I

138

PLAN
( SHOWING POSITION OF LINKS )

Fig. 9.20 Stirupps— Vertical Links

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNG

SP : 34(S& T)-1987

COLUMN

r STIRRUPS

PROVIDE FIXING BARS
WHERE MAIN BARS ARE
NOT PRESENT

SECTION

PLAN

Fig. 9.21 Beam-Cage Stirupps (Supplemented by Isolated Stirrups).

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

139

SP : 34(S&T)-1987

COLUMN

O'Sd
• i- rBENT UP BARS

SECTION

0-25 d

PLAN

Fig. 9.22 Bkam-Cage Stirrups (Supplemented by Bent-up Bars).

140

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

%,0F COLUMN-s^

--E

•J

t.OF
.COLUMN

II I

ljljl^uj
rTr-ir-ir-ir-ir-ir-;r-ir-unrnrir-jrTr

L^LJL.JC.JI.JL.Ji..i«..iL.JLJL.jL JLJLJL

• I

- . II i» I* II »i I

— I
-J

r-|r-tr-Tr-|r-»r-ir-irT

L^LJU.JLJLJI.JLJtJ

r-Tr-mir-1

*. L.JLJLJLJ ^

^ r- -ir-ir-ll-l / L

ALU L^^JL * ''

• I

:« II n I* !

-J N.-L'^ I.-1LJI.JLJ V. L ^

-"1 r-irir-i«*-»

.^ _i L.JI..IL.IL-J

-ii"-lf-il»--f»— ir-ii — irni — ir-i*-nr"^f
•» i- «•« ii ii ii II If |i i li if

r-ir-ir-»rirnr"ir-

I tLjL JL. JL Ji^jL.

r-iT-ir-irn

*^ L.jL-JL.Jl.J

L JU JUJL .J

r-ir-ir-^r-i

ir-ir-ir-|r-|nr-
I « 11 II If it

mi m

INTERIOR PANEL

» N

EXTERIOR PANEL

LAYOUT PLAN

t. SUPPORT

I /-TRUSS
BAR

STRAIGHT
BAR

TRUSS
BAR

SECTION THROUGH COLUMN STRIP

TOP BAR

SECTION THROUGH MIDDLE STRIP

Fig. 9.23 Typical Arrangement of Bars in a Waffle Slab

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILINC;

141

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 10

Stairs

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T).|9«7

SECTION 10
STAIRS

10.0 Introduction — Reinforced concrete stairs
are self-supporting or carried on beanis or walls.
They are often built around open or lift wells
supported according to the type of structure.
Staircase with cantilevering treads from a column
or wall support are also commonly used for fire
escape stairs, etc.

Note — Minimum steel, bar spacing and cover should
conform to the requirements specifled for slate and
beams as appropriate.

10.1 Flight SupiK>rted on Side Beams — The

reinforcement detail for a staircase supported by
edge beams alon^ each edge is similar to the one
supported along its edges by a brick wall. Figure
10.1 shows cross-sectional details of a flight with
two types of arrangements.

TP^

CtCAU SPAW

OUTOO-ISt

£T«UM

WIDTH

lO.lA

0-tl lOO-ISl

lO.IB

Fig. 10. 1 Typical Cross-Section of Staircase
Supported on Side Beams

10.2 Flight Supported on CentrmI Beam —

Figure 10.2 shows the cross-sectional detail of a
typical staircase supported on a central (stringer)
beam. Each step of the staircase is acting as a
cantilever on both sides of the main beam.

_ 1 —

-r^-1

1 1 1

1 -J

iw^

Fig. 10.2 Typical Cross-Section of a Flight
WITH A Central Beam

10.3 Flights and Landings Supported at Ends —

Figures 10.3 and .10.4 illustrate two types of stairs
with flight and landing supported at ends.
Figure 10.3 gives reinforcement details of a flight
spanning from outer edge to outer edge ot
landing. Figure 10.4 gives reinforcement details of
a flight together with its landings spanning from
inner edge to inner edge of landings.

10.3.1 Flight Supported on Brick Wall —
Figure 10.5 shows the elevation detail for a
straight stair flight with its landings at its ends
supported by brick walls.

10.4 Cranked Beams — Straight stairflights and
landings supported by side or centre beams as
shown in Fig. 1 0.1 to 10.3 will require cranked
beams. The elevation details of cranked beam is
shown in Fig. 10.6.

The method of reinforcing a cranked beam is
shown in Fig. 10.6. The bars at the intersections
shall be carried for development length past the
intersection, and one set of bars shall be cranked
inside the other because of fouling. To complete
the intersection extra bars, normal to the angle of
intersection, are usually added as shown by the
bars € and /.

10.5 Cantilever Stairs — A typical details of a
tread cantilevering from a wall is given in
Fig. 10.7. A typical detail of a staircase
cantilevering from the side of a wall is shown in
Fig. 10.8.

10.6 Slabless Tread Riser Stairs — A typical
detail of a slabless tread riser staircase is given in
Fig. 10.9.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

145

SP : 34(S&T)-1987

ROW OF CHAIRS

NOSING
REINFORCEMENT

SLAB THICKNESS

REtNFT.ASPERDESIG)

ROW OF CHAIRS

BRICK STEPS

MAIN STEEL

01 ST. STEEL -I

DETAIL -X
(WITH BRICK STEPS)

Fig. 10.3 Stairs Supported at Ends of Landings— Showing Position of Main
Reinforcement

146

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T>-1987

FLOOR LEVEL

OW OF
CHAIRS

X = GREATER OF OTSl OR L^

W INTERMEDIAT E LANDING

ROW OF
CHAIRS

PLINTH

FOOTING

Fig. 10.4 Stairs Supported at Ends of Flights— Showing Main Reinforcement

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

147

SP : 34(S&T)-I987

#* FLEXIBLE
V^ > MATERIAL MO

DISTRIBUTION STEELi

jfiBBsft

FLEXIBLE
MATERIAL
PAD

X >50% UP TO 0-251)
50% UP TO 0151)

1 rjLAP ^

TENSION

.BRICK WALL

Fig. 10.5 CROSS-SiiCTioNAL Di-tails of a Single Span Straight Flight Supportid on
Brick Walls

Fig. 10-6 Cranked Beam

MAIN REINFORCEMENT •
-DISTRIBUTION STEEL

.REINFORCEMENT
IF REQUIRED

• SO % OF MAIN REINFORCEMENT
CAN BE CURTAILED AT A
DISTANCE OF OS I OR L4 FROM
THE FACE OF SUPPORT

148

Fig, 10.7 Steps Cantilevering from a Concrete Wall

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

LINKS AT 300 mm
UNLESS OTHERWISE
SPCCtnED

MAIN BARS
AS PER

DESIGN

U-8ARS

DISTRIBUTION BARS AT
300mm UNLESS
OTHERWISE SPECIFIED

* *

. J. CORNER BAR DETAI
V-[T^ / WITH WALL

LEO

^~ — :

-f/

«^7 ■■

—4

U-BAMSINOMINAII— J

SP : 34(S&T>-1987

10.10 Where construction requires bars larger
than # 10 or 16 should not be detailed to be
rebend, but mild steel bars are recommended if
rebending is unavailable.

3" HOLDING 8ARS

SECTION -AA

Fic- !0.8 Typical Details of a Stair Case
Cantilevering from the Side of a
Wall

10.7 Staircases are normally detailed
diagrammatically in plan or section. This is best
done by arranging the placing detail and bending
schedule adjacent to one another on a single
drawing sheet {see Fig. 10.10).

10.8 Re-entrant Comers — When tension bars
meeting at a corner produce a resultant force
resisted by the concrete cover, the bars shall be
crossed over and anchored on either side of the
cross-over by adequate anchorage length for
taking up the stresses in the bar (see Fig. 10.11).

10.9 Hand Rail Supports — The designer should
ensure that adequate consideration is given to the
reinforcement detailing for hand rail supports. If
pockets are left in the concrete into which the
hand rail posts are later concreted, the
reinforcement shall pass around \the pockets and
be anchored into the main body of the concrete. If
inserts are set into the concrete these should have
steel bars passing around them to have sufficient
anchorage ties build-in.

ALTERNATIVE!

ALTERNATIVE -n

Fig. 10.9 Typical Details of a Slabless Tread
Riser Staircase

HANDBOOK ON CONCRETE REINFORCEMENT AND Di-T

149

H^MBEi^

MARK SIZE TW

REtNFORCEMENT

SLAl A
CCONTINUEO)
GROUND -
FLOOR

TfVPE

STAIRS
OROUNO -
FIRST
FLOOR No.1

SLAB A

FIRST

FLOOR

29
6
3
5

2
10

#-10
#10

♦a

<»a

#10
#10

MARK

#to

#10

totSl

N0.

10
M

2
6

LENGTH

10
10

3
5

3100
2066

2000
U50
3400

g_2M

220

<,^2»0

T ?ro 9 120

' STR

STR

5000

2260
USD
3200

3A00

120 J

iftQ I 3300

aio

J-J^

JSSL

120

.iZSSL

N^60(

?o^

260

STR

FIRST floor

F F M

ground floor

.520,1

2 f 8- F If f1

10 #10-0

Fig. 10.10 An Example of a Stair with Placing Detail and Bending Schedule

SP : 34(S&T)-1987

L^ (MiN.)

Fig. IO.I I Requirements for Tension Bars Crossing each other at a Point

„^j.^55»OOK ON CONCRETE REINFORCEMENT AND DETAILING

151

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 11

Special Structures — Deep Beams, Walls, Shells and Folded Plates,
Water Tanks, RC Hinges, Concrete Pipes, Machine Foundations, and

Shear Walls

As in the Original Standard, this Page is Intentionally Left Blank

SV : 34(S&T)-1987

SECTION 11

SPECIAL STRUCTURES -DEEP BEAMS, AVALLS, SHELLS AND

FOLDED PLATES WATER TANKS, RC HINGES, CONCRETE PIPES,

MACHINE FOUNDATIONS, AND SHEAR WALLS

11.1 Deep Beams — A beam shall be deemed
to be a deep beam when the ratio of effective
span to overall depth (//D) is less than:

a) 2.0 for simply supported beam, and

b) 2.5 for a continuous beam.

11.1.1 Reinforcement

11.1.1.1 Positive reinforcement — The
tensile reinforcement required to resist positive
bending moment in any span of* a deep beam
shall:

c) be placed within a zone of depth equal to
(0.25 D~-0.05 /) adjacent to the tension
face of the beam where D is the overall
depth and / is the effective span. The arran-
gement is illustrated in Fig. II.I.

Note I — Anchorage of positive reinforcement may be
achieved by bending of the bars in a horizontal plane (see
Fig. 1MB).

Note 2 — The main reinforcement may be supplemented
by two layers of mesh i-einforcement provided near each of
the two faces; in which case the spacing between two
adjacent parallel bars must not exceed twice the thickness of
deep beam or 300 mm, whichever is greater.

a) extend without curtailment between
supports;

b) be embedded beyond the face of each
support so that, at the face of the support, it
shall have a development length not less
than 0.8 La; where L^ is the development
length for the design stress in the reinforce-
ment (Fig. 11.1);

11.1.1.2 Negative reinforcement

a) Termination of reinforcement — For tensile
reinforcement required to resist negative
bending moment over a support of a deep
beam:

1) it shall be permissible to terminate not
more than half of the reinforcement at a

NOMINAL HORIZONTAL
RElNFORCEMeNT PROVIDED
IN COMPRESSION ZONE

NOMINAL VERTICAL
STIRRUPS

^ —

1 1

i:;

LXI

1:-

L- POSITIVE FLEXURAL
REINFORCEMENT

fr'

ADDITIONAL
REINFORCEMENT
NEAR SUPPORT

0-25 D
0-051

END BARS ARE TO BF.
ANCHORED FOR A
DISTANCE OF 0*eLtf
AT BOTH SUPPORTS

Fig. 11.1 Reinforcemenj Detailing in Simply Supported Deep Beams iCominued)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

155

SP : 34(S&TH987

■^^ ■

, BEAMNe ^

t 1

LOECF BEAM
SECTION

ot ^

»> W l

Fig. M.I Reinforcement Detailing in Simply
Supported Deep Beams

distance of 0.5 D from the face of the
support; and

2) the remainder shall extend over the full
span.

b) Distribution steel — When ratio of clear
span to overall depth is in the range 1.0 to
2.5, tensile reinforcement over a support of a
deep beam shall be placed in two zones
comprising:

!) a /.one of depth 0,2 /), adjacent to the
tension face, which shall contain a
proportion of the tension steel given by

0.5(-^-0.5)

where

/ = clear span, and

D - overall depth.

2) a zone measuring 0.3 D on either side of
the mid-depth of the beam, which shall
contain the remainder of the tension
steel, evenly distributed.

For span to depth ratios less than unity, the
steel shall be evenly distributed over a depth of
0.8 D measured from the tension face. Figure 1 1.2
shows the disposition of this reinforcement.

11. 1.1 J Vertical reinforcement — If forces
are applied to a deep beam in such a way that
hanging action is required, bars or suspension
stirrups shall be provided to carry all the forces
concerned {see Fig. 1 1 .3 A).

11.1.1.4 Side face reinforcement ~ Side
face reinforcement shall comply with
requirements of minimum reinforcement for
walls.

11.1.1.5 Stirrups for deep beams — To
stiffen the legs of stirrups for deep beams against
buckling during construction, tie clips to the legs
and horizontal bars. Space the clips horizontally
at every second or third stirrup, subject to a
maximum space of 600 mm, and vertically at
alternate intersections of horizontal bars (see
Fig. 1I.3B).

11.2 Walls — This clause deals with reinforced
concrete walls other than retaining walls.

Note — A wall is a vertical structural element whose
length exceeds four times its thickness. A wall containing
only minimum reinfocement which is not considered in
design forms a plain concrete wall.

11.2.1 Walls to Carry Vertical Loads —
Where reinforced concrete walls are intended to
cany vertical loads, they should be designed
generally in accordance with the recommenda-
tions given for columns. The provisions with
regard to transverse reinforcement to restrain the
vertical bars against buckling need not be applied
to walls in which the vertical bars are not assumed
to assist in resisting compression. The minimum
reinforcement shall be as specitied in 11.2.1.1. The
minimum thickness of wall should not be less
than 100 mm.

11.2.1.1 Reinforcement — The minimum
reinforcement for walls shall be provided as given
below:

a) The minimum ratio of vertical reinforcement
to gross concrete area shall be 0.004 (irrespec-
tive of type and grade of steel).

b) Vertical reinforcement shall be spaced not
farther apart than three times the wall
thickness or 450 mm, whichever is less.

c) The minimum ratio of horizontal
reinforcement to gross concrete area shall
be:

1 ) 0.002 for deformed bars not larger than
16 mm in diameter and with a
characteristic strength of 415 N/mm^ or
greater.

2) 0.002 5 for other types of bars.

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HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

CONTINUING
BARS

A,jtNlt IN THIS CASE)

o5o

ll.2ACi,EAR SPAN OVERALL DEPTH {A)»2-5

CONTINUING
BARS
CURTAILED
BARS

Asi - 0-SA,

IL2BCLEAR SPAN OVERALL DEPIH («S»1*5
ALL BARS CONTINUING /—A,

0^0

JTl

^ H

IL2CCLEAR SPAN OVERALl OIPIH t^J^fc^*®
A. = AREA OF NEGATIVE REINFORCEMENT

Fig. 1 1 .2 Disposition of Negative Reinforcement in Continuous Deep Beams

3) 0.002 for welded wire fabric not larger
than 16 mm in diameter.

d) Horizontal reinforcement shall be spaced
not farther apart than three times the wall
thickness or 450 mm.

e) In case of plain concrete walls (where
vertical load is not predominant) quantity
of vertical reinforcement given in (a) shall be
modified as follows:

1) 0.0012 for deformed bars not larger than
16 mm in diameter and with a charac-
teristic strength of 415 N/mm^ or greater.

2) 0.0015 for other types of bars.

3) 0.0012 for welded wire fabric not larger
than 16 mm in diameter.

11.2.2 IVa/is to Resist Moment and Shear ^
Horizontal wall reinforcement may be required

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIIJNG

157

SP : 34(S&T)-1987

SUSPENDED
IRRUPS

r-^

A^0-002bwS

REDUCED LENGTH
OF STIRRUPS
NEAR SUPPORT

D OR I

POSITIVE FIEXURAL
REINFORCEMENT WITH
END ANCHORAGE

Fig. II. 3 a

CUP AT 2P OR 3P
C|C ( eOO MAX.)

MAIN STIRRUP

MAIN STIRRUP
AT P C|C

5 C

3 C

D C

3 C

> C

> C
3 fi

2^-fi

SUSPENDED
STIRRUPS

SECTION

ELEVATION

Fig. 1I.3B
Fig. 1 1.3 Suspended Bars for Deep Beams

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HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

by the designer to resist moment, shear or merely
changes in length due to temperature or
shrinkage. In any case, unless the designer
indicates a shrinkage control joint at this point,
all the horizontal bars in one or sometimes both
faces of a wall should be sufficiently extended
past a corner or intersection for development
length (see Fig. 11.4). Nevertheless it is necessary
for the designer to indicate which, if any,
horizontal reinforcement should be extended for
full development at intersections and corners of
walls and footings. Typical details are shown in
Fig. 11.4 for resistance against moment inward,
outward, or both with the reinforcement from the
appropriate face or faces anchored. Figure 11.5
shows a cross-section through floors and walls
indicating general arrangement of reinforcement.

n.2.3 Thin Walls — \n case of thin walls,
reinforcement has to be detailed in such a way
that the concrete can be thoroughly compacted.

For walls of thickness !70 mm or less, where the
insertion of a vibrator may lead to difficulties, a
single layer of vertical and horizontal bars may be
provided at the centre of the wall and an external
vibrator may be used {see Fig. II.6A).

\\,1A Thick Walls ~-\n case of walls of
thickness greater than 170 mm but less than or
equal to 220 mm, and also for walls of thickness
greater than 220 mm with more than nominal
reinforcement, provide two layers of rein-
forcement in both vertical and horizontal
directions, the former being placed on the inside
of the latter (see Fig. I1.6B). Clips should be
provided to restrain the vertical bars against
buckling or displacement during concreting. In
walls of thickness greater than 220 mm with
nominal reinforcement, horizontal steel may be
placed inside the vertical steel to reduce the
possibility of the coarse aggregate being *hung-up'
on the horizontal bars {see Fig. !i.6C).

LAP

■ ■ i

'Q]

j LAP

11. 4A

1.4B

THESE TWO BARS REQUIRED FOR
WALL THICKNESS LESS THAN 300 mm
FOR WALL THICKNESS GREATER THAN
300 mm k BARS REQUIRED

I1.4C

II.4D

Fig. 1 1.4 Typical Corner and Intersection Details for Reinforced Concrete Walls

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING I5*>

SP : 34(S&T)-1987

LAP LENGTH

FLOOR UEVEI

U-BAftS

VERTICAL BARS
ON KICKER

LAP LENGTH

FOUNDATION

Note — Horizontal bars are placed outside vertical bars

Fig. 11.5 General Cross-Sectional Details of Walls

11.2.4.1 Walls with vertical reinforcement
close to or more than 0.4 percent of the plan mea
of concrete — In heavily reinforced walls (with
vertical reinforcement close to 0.4 percent of the
plan area of concrete), the following requirements
should be satisfied:

a) Ensure that clips are provided for vertical
bars at a horizontal spacing not exceeding
twice the wall thickness.

b) Vertical bars that are not fully restrained are
placed within a centrc-to-cehtre distance of
200 mm. from a bar that is fully restrained.

c) Vertical spacing of clips should not exceed
15 times the diameter of the vertical rein-
forcement or 300 mm whichever is the lesser.

d) At all splices, the top of each lower bai
and the bottom of each upper bar are res-
trained by means of clips.

e) Preferably clips (alternately reversed) may
be used, or alternately, truss-type clips as
indicated in Fig. 11.7 may also be used.

11.2.5 Splices at Top of W^a// — Whenever a
slab is to be cast at the top of a wall, detail the
vertical continuity of steel from the walls into the
top of the slab as follows:

a) If the diameter of deformed bars is less thai)
or equal to 10 mm, the straight bars can be
bent into the slab as shown in Fig. 11. 8 A.

b) If the diameter of deformed bars is greater
than 10 mm, the details shall be as shown in
Fig. 1L8B or IL8C

c) If mild steel bars (any diameter) are used,
they can be safely bent into the slab without
any damage.

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HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

HORIZONTAL BARS
TIED TO VERTICAL

.HORIZONTAL BARS
/TIED TO VERTICAL

CUPS CONNEaiNG
THETWOUYERSOF
VERTICAL REINrO-
RCEHENT.

CLIPS CONNECTING
THE TWO LAYERSOF
HORIZONTAL REINF-
ORCEMENT.

VERTICAL BARS TCO-^
TO HORIZONTAL BARS

SP : 34(S&T)-1987

1I.6A WALLS OK THICKNESS

^ 170 mm. REINFORCEMENT

IN CENTRE OK WALL (CONSIDERED

TO BE NOMINAL)

1L6B WALLS OF THICKNESS n.6C WALLS OF THICKNESS

>170 mm BUT ^220 mm >220 mm WITH NOMINAL

AND WALLS OF THICKNESS REINFORCEMENT

>220 mm WITH VERTICAL
REINFORCEMENT GREATER
THAN NOMINAL

Note — Position of Clips to be Indicated on the Drawing

Fig. 11.6 Vertical Sections for Walls

TRUSS TYK
aiPSMALTCRHATt LAYERS

Fig. 1 1.7 Truss-Type Clips in Alternate
Layers in a Wall

11.2.6 Walls Constructed by Means of Sliding
or Climbing Shuttering — Detailing of walls to be
constructed by sliding or climbing shuttering is
affected by constructioji techniques that are often
unique to the system involved. These techniques
include, for example, the use of jacking rods and
spacers, are reliant on casting cycles, have
separation problems, and depend upon a variety
of factors that require special detailing, and
should thus be planned in conjunction with the

contractor. In general, connections to slabs and
beams are by means of chases or pockets (or
both) as it is not generally feasible to leave splice
bars protruding from the walls. Splice bars to be
bent out should normally be not larger than # 10
or 016. If heavier splices are required and it is
not possible to provide pockets of adequate size,
consider the use of mechanical splices or welding.

When sliding shuttering is used for walls,
vertical splices should preferably be staggered to
ease placing problems and to prevent the
displacement of reinforcement during sliding.
Placing details should call attention to adequate
wiring together of upper and lower reinforcement.

11.3 Retaining Walls — The shape of a retaining
wall is a function of various factors including the
natural and final ground profiles, the proximity of
and relationship to existing and proposed
buildings and services, the economics of cut and
fill, the properties of the filling material, external
and subsurface drainage, and vertical and
surcharge loads. As a result there are different
types of retaining walls, for example, cantilever
walls with Ly T, and reversed L bases.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

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SP : 34(S&T)-1987

■4-

SLAB

WALL

II, 8 A

n.8B

U- TYPE BARS

SLAB

WALL

n.8C
Fig. 1 1,8 Splices at Top of Wall

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HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&TV1987

counterforted walls, crib walls, propped and
semipropped walls; each type of retaining wall
requiring its own individual reinforcing technique
(see Fig, 11.9 to 11.12). However, the same
general principles apply to all, the more important
of which are as follows:

a) So detail the reinforcement as to keep the
placing as simple as possible and to
minimize difficulties on site which are often
compounded by the conditions under which
the work is carried out.

b) So arrange the distribution of reinforcement
(which is governed by design) as to allow for
adequate continuity and to avoid abrupt
termination of steel by the staggering of
laps.

c) Carefully control the cover to steel on faces
adjacent to earth. This applies especially to
faces where concrete is to be cast against
excavation, for example in footings where
the use of levelling course fs recommended.

d) So detail expansion joints in the wall as to
ensure that relative movements of
continuous sections are minimized by the
transfer of shear across joints.

e) Ensure that at joints steel detailing caters for
the incorporation of water-bars when
required.

f) Note that extra reinforcement may be
required to meet additional stresses induced
by heavy earth compaction and by shrinkage
in the wall against the restraint of such
compacted earth especially between
counterforts.

g) Provide minimum horizontal reinforcement
as per 11.2.1.1 (c) and minimum vertical
reinforcement as per 11*2.1.1 (e).
The steel (indicated by a dotted line in Fig.
11.9 to 1 1. 11) facilitates the maintenance in
position of main bars during concreting.

h) Take account of the reduction of
effectiveness of reinforcing at corners,
especially at re-entrant or opening corners.
The inclusion of fillets and splay bars in the
case of reversed L bases is recommended.

j) In the case of cantilever walls, place the
vertical steel on the outer layer to take
maximum advantage of the available lever
arm. Horizontal bars may be placed on
outside for exposed faces.

k) Ensure that provision is made for the
structure above or beyond the wall where
the required information relating to the
continuity of the reinforcing must be
provided.

(SEE CLAUSE 1VM)

# -REINFORCEMENT Al SAME PLANE

Fig. n.9 L-Walls (Distribution Bars Omitted Fig. II.IOT-Walls (Distribution Bars

FOR Clarity) Omitted for Clarity)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

163

SP : 34(S&T)-1987

COLUMN ABOVE

COLUMN
STARTERS

'o!v^^|ff4iW"

FULL LAP
LENGTH

(DIMENSION TO
BE GIVEN)

REINFORCEMENT AT SAME PLANE

Fig, I flJTl Reversed L-Bases (Distribution
Bars Omitted for Clarity)

m) Note that the radius of bends tor the main
tensile bars is critical and should be at least
7.5 bar diameters,

n) If problems are encountered in the
accommodation of bars at the intersection
of the base and wall, consider reducing the
bar diameters and increasing the member
thickness.

p) Kicker height below ground level should be
a minimum of 150 mm.

q) Full contraction joints should only be used
when it is predicted that shortening along
the full length of the wall will be cumulative.
Where necessary they should be detailed at
30 m centres. Movement joints should only
be used when there is a risk of differential
settlement between adjacent members.

11.3.1 Counterfort Re taming Wall — Vigwrt
11.13 shows an elevation and section of a typical
counterfort retaining wall illustrating general
arrangement of reinforcement.

As with the wall part, the bars projecting from
the base into the counterfort act as starter bars
and must be of sufficient length to allow for
lapping. These bars will normally be ^/-shaped.
The wall is anchored to the counterfort by
extending the binders from the counterfort into
the wall. Opportunity has also been taken in Fig.
II. 13 of showing the steel arrangement in the wall
where it is anchored to the counterfort. It will be

Note — Precise layout of reinforcement depends upon full
analysis.

Fig. 11.12 Propped Retaining Walls

seen that the arrangement is exactly the same as
for a continuous floor slab supported on beams,
the beams being on the opposite side of the wall
to that of the counterforts,

11.4 Shell and Folded Plate Structures

11.4.1 General ^S)^Q\\s and folded plates
belong to the class of stressed skin structures
which, because of their geometry and small
flexural rigidity of the skin, tend to carry loads
primarily by direct stresses acting on their plane.
Different types of reinforced concrete shell and
folded plate structures are in use in present day
building practice for a variety of applications and
give roofing of large column-free areas.

Cylindrical type shells are relatively common
although shells of double curvature with the
exception of domes have been introduced lately
into building construction. However their use is
limited as they demand exceptionally high degree
of workmanship and costly formwork.

Folded plate structures are composed of
rectangular plates/ slabs connected along the
edges in such a way as to develop special rigidity

164

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : S4(S&T)-1987

of component parts. Their structural behaviour
consists of transverse slab action by which the
loads are carried to the joints, and longitudinal
plate action by which they are finally transmitted
to the transverses. Because of its great depth and
small thickness, each plate offers considerable
resistance to bending in its own plane.

Folded plates are often competitive with shells
for covering large column free areas. They usually

COUNTERFOUt

-5

KEY J

!s!:iJiiiiiiirk\^

miiiiiu

HCCL

SECTION -AA

vi If h

PLAN

consume relatively more materials compared to
shells, but this disadvantage is often offset by the
simpler formwork required for their construction:
The added advantage of folded plate design is that
its analysis is simpler compared to that of shells.

For detailing of reinforcement in shells and
folded plates, the provisions of *IS : 2210-1962
Criteria for the design of reinforced concrete shell
structures and folded plates* are normally
followed,

11.4.2 Diameter and Spacing of Rein-
forcement — The following diameters of bars may
be provided in the body of the shell/ plate. Large
diameters may be provided in the thickened
portions. Reinforcement in the form of welded
wire fabric may also be used to satisfy design
requirements:

a) Minimum diameter : 6 mm

b) Maximum diameter:

1) 10 mm for shells between 4 and 5 cm in
thickness,

2) 12 mm for shells between 5 and 6.5
cm in thickness, and

3) 16 mm for shells above 6.5 cm in
thickness.

The maximum spacing of reinforcement in any
direction in the body of the shell /plate shall be
limited to five times the thickness of the shell and
in the area of unreinforced panels to 15 times the
square of thickness.

The cover requirements to reinforcement shall
be as per slabs.

11.4.3 Reinforcement in Shells — The ideal
arrangement would be to lay reinforce-
ment in the shell to follow isotatics, that
is, directions of the principal tensile stresses
assumed to act at the middle surface of the plate.
However, for practical purposes, one of the
following methods may be used:

One is the diagonal grid at 45® to the axes ol
the shell, and in the other the rectangular grid in
which the reinforcing bars run parallel to the
edges of the shell. The rectangular grid needs
additional reinforcement at 45° near the supports
to take up the tension due to shear.

11.4.3.1 In the design of the rectangular
grid for cylindrical shells, the reinforcement shall
be usually divided into the following three groups:

a) Longitudinal reinforcement to take up the
longitudinal stress T^;

b) Shear reinforcement to take up the principal
tension caused by shear S; and

Fig. 11.13 Typical Details of a Counterfort
Retaining Wall

c) Transverse reinforcement to resist T. and

My.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

165

SP : 34(S&T)-1987

/ /

11.4.3.2 Longitudinal reinforcement shall
be provided at the junction of the shell and the
traverse to resist the logitudinal ^nwment M^,
Where Mx is ignored in the analysis, nominal
reinforcement shall be provided.

11.4.3.3 To ensure monolithic connection
between the shell and the edge members, the shell
reinforcement shall be adequately anchored into
the edpe members and traverses or vice-versa by
providing suitable dowel bars from the edge
members and traversies to lap with the shell
reinforcement.

11.4.3.4 r/iic/cnesj — Thickness of shells
shall not be normally less than 50 mm if singly
curved and 40 mm if doubly curved. Shells are
usually thickned to some distance from their
junction with edge members and traverses. The
thickening is usually of the order of 30 percent of
the shell thickness. In the case of singly curved
shells, the distance over which the thickeni ng is
made should be between 0.38v^and Q.ldyJRj,
where R and d are the radius and thickness,
respectively. For double curved shells, this
distance will depend upon the geometry of the
shell and boundry conditions.

11.4.4 Reinforcement in Folded Plates

11.4.4.1 Transverse reinforcement —
Transverse reinforcement shall follow the cross-
section of the folded plate and shall be designed
to resist the transverse moment.

1,1.4.4.2 Longitudinal reinforcement —
Longitudinal reinforcement, in general, may be
provided to take up the longitudinal tensile
stresses in individual slabs. In folded plates which
arc like beams, the longitudinal reinforcement
may be provided for the overall bending moment
on the span treating the folded plate as a beam.
The section of the concrete and transverse
reinforcement at the joint shall be checked for
shear stress caused by edge sheer forces.

11. 4.4 J Reinforcement bars shall prefer-
ably be placed, as close as possible so that the
steel is well distributed in the body of the slab.
Nominal reinforcement consisting of 10 mm bars
may be provided in the compression zones at
about 20 cm centre-to-centre. ^

11.4.4.4 Thickness — Iht thickness of
folded piaics shall not normally be less than 75
mm. It is sometimes advantageous, while using
the trough shape, to make the horizontal plates
thicker than the inclined ones.

11.43 Typical details of placing reinforcement
m shells and folded plates arc shown in Fig. 11.14
to n.l7.

11.5 Reservoirs and Tanks — The rescfvoirs and
tanks for storage of liquids can be square,
rectangular, circular or hexagonal in plan with a
roof over them. One of the important detailing
considerations is the sealing of the construction
joints and the same should be detailed on the
drawing. The grade of concrete below M 20 shall
not be used for sections of thickness equal to or
less than 450 mm. Tanks shall generally be
designed as uncracked section.

11.5.1 Cover — Minimum cover to
reinforcement of members on faces either in
contact with the liquid or enclosing space above
the liquid (such as inner face of roof slab), should
be 25 mm or the diameter of the main bar,
whichever is greater. In the presence of sea water,
soils and water of corrosive character, the cover
shall be increased by 12 mm but this additional
cover should not be taken into account for design
calculations.

11.5.1.1 For faces away from the liquid and
for parts of the structure not in contact with the
liquid, the cover shall conform to requirements of
Section 4.

11.5.2 Minimum Reinforcement —'\\\t
minimum reinforcement in walls, floors and roofs
in each of two directions at right angles shall have
an area of 0.3 percent of the concrete section in
that direction for sections up to 100 mm thick.
For sections of thickness greater than 100 mm
and less than 450 mm the minimum reinforcement
in each of the two directions shall be linearly
reduced from 0.3 percent for 100 mm thick
section to 0.2 percent for 450 mm thick section.
For sections of thickness greater than 450 mm,
minimum reinforcement in each of the two
directions shall be kept at 0.2 percent. In concrete
sections of thickness 225 mm or greater, two
layers of reinforcement shall be placed one near
each face of the section to make up the minimum
reinforcement.

11.5.2.1 The minimum reinforcement
specified in 11.5.2 may be decreased by 20 percent
in case of high strength deformed bars.

11.5.2.2 In special circumstances such as
tanks resting on ground floor slabs, percentage of
steel less than that specified above may be
provided.

11.5.3 Joints

11.5.3.1 General — This clause defines the
types of joint which may be required in liquid-
retaining structures. The types of joints are
illustrated in Fig. 11.18 and are only intended to
be diagrammatic. The location of all joints should
be decided by the engineer and shall be detailed
on the drawings.

11.5.3.2 Types of joint

a) Construction joint — \ construction joint
is a joint in the concrete introduced for

166

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

REINFORCEMENT OVER
ENTIRE SHELL

(SPACING VARIED ACCORDING
TO DESIGN )

TOP REINFORCEMENT AT
DIAPHRAGM ANCHORED
ACCORDING TO END CONDITION

SQUARE MESH ALTERNATE
TO DIAGONAL BARS

^-LONGITUDINAL TENSILE
BARS IN THE EDGE MEMBER

V ADDITIONAL DIAGONAL BARS ANCHORED
IN EDGE MEMBERS OR DIAPHRAGM

I1.14A iSO METRIC VIEW OF A BARREL SHELL

INTERMEOtATE
EDGE MEMBER

M.14B REINFORCEMENT NEAR AN INTERMEDIATE EDGE MEMBER

0-1 Li , OUi

' I 1 I

I ■ i

^ ^INTERMEDIATE

DIAPHRAGM

It !4C REINFORCEMENT NEAR AN INTERMEDIATE DIAPHRAGM

Fig. 11.14 Typical Management of Bars in a Long Barrel Shell

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

167

SP : 34(S&T)-1987

1.I5A AT EDGE MEMBERS

^ OH?

*^^

■I ■

. 0-^«'2 .

i i ■ ^

INTERMEDIATE
DIAPHRA6H

1 1. 158 ABOVE INTERMEDIATE DIAPHRAGMS

Fig. 11.15 Typical Details of a Short Barrel Siihll

1«8

Fig. 11.16 Rkiniorckment in a Domk

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNG

SP : 34(S&T>-1987

ELEVATION SHOWING PROFILE

r-TRANSVERSE STEEL *«*
mo 250

^TRANSVERSE STEEL 'd*
fU ID 2S0

ai-

iSO l. 1050 J-4S0.L 1050 I,i50,

5000

HALF PLAN OF FOLDED PLATE ROOF

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

169

SP : 34(S&TH987

<tt100

2-^16

m»2oo

2-^12

3-#22

L3-*22

<a)4oo

6000

^10 STIRRUPS

2-tl6

a 200

SECTIONAL ELEVATION OF DIAPHRAGM

fl>100^

6-422

^\o&m STPS.

-22

:22

DETAIL AT- F

SECTION- DD

SECTION- EE

6000

2^t20

SECTION-AA
Fig. 11.17A

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HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(Sft1>1987

SECTION -A A
iSfiO.

H»

SECTION -BB

1000

SECTION- CC

Fig. 11.17

convenience in construction at which
measures are taken to achieve subsequent
continuity with no provision for further
relative moment. A typical application is
between two successive lifts in a tank wall
(see Fig. 11.18A).

b) Movement joirit,— A inoyement joint is a
specially formed joint intended to accom-
modate relative movement between adjoin-
ing parts of a structure, special provision
being made for maintaining the water-tight-
ness of the joint. Movement joints may be of
the following types:

1) Contraction Joint — This is a movement
joint which has a deliberate discontinuity

but no initial gap between the concrete
on both udes of the ^int. The joint is
intended to permit contraction of the
concrete.

A distinction should be made between
a complete contraction joint (see
Fig. I1.18C), in which both the concrete
and reinforcement are interrupted, -and
a partial contraction joint (see Fig.
11J8B), in which only the concrete is
interrupted while the reinforcement is
continued through the joint.

2) Expansion Joint — This is a movement
joint #hich has complete discontinuity in

HANHBOOK on concrete reinforcement and DETAIUNG

171

SP : 34(S&T)-1987

both reinforcement and concrete and is
intended to accommodate either expan-
sion or contraction of the structure {see
Fig, II.I8D).

3) Sliding joint — This is a movement joint
which has complete discontinuity in both
reinforcement and concrete. Special
provision is made to facilitate relative
moment in the plane of the joint. A typi-
cal application is between wall and floor
in some cylindrical tank designs'

U,5.4 Rectangular Tanks

11.5.4.1 General — Rectangular water tanks
are generally analyzed in accordance with
IS : 3370 (Part 4)-1967 Code of practice for
concrete structures for storage of liquids: Part 4
Design tables'. This code gives tables for moment
coefficients and shear coefficients for fixed wall
panels along vertical edges but having different
end conditions at top and bottom. In arriving at
these coefficients, the slabs have been assumed, to
act as thin plates under various edge conditions
given in the code.

CONCRETE JOINT TO BE
PREPARED FOR
SUBSEQUENT CONTINUITY

SECOND STAGE

STEEL CONTINUITY

FIRST STAGE

Fig. 11.18A A Construction Joint

JOINT SEALING
COMPOUND

NO CONCRETE
CONTINUITY AND
NO INITIAL GAP

r,*.yv^*

SEALING COMPOUND
ON ONE OR BOTH
FACES

CONCRETE
CONTINUITY AND
NO INITIAL OAP

WATER8T0P F DESIRED

» .• V . . ^NO STEEL
CONTINUITY

WATERSTOP

I1.18B PARTIAL CONTRACTION JOINT II. ISC COMPLETE CONTRACTION JOINT

Fig. 11.18 Types of Joints (To Illustrate Basic Principles) (Continued)

>" handbook on CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-I987

NON-ABSORBENT
JOMt FILLER

NO ItEEL
CONTINUITY

SEALING
COMPOUN D

INITIAL GAP
FpR EXPANSION

EXPANSION TYPE
WATERSTOP

n,l8D EXPANSION JOINT

Fig. 1 1.18 Types of Joint (To Illustrate Basic Principles)

In the plan, the corners restrain the walls under
pressure from their tendency to bend outward {see
Fig. 1 1.19). This produces tension zones as shown
in Fig. 11.19, at the middle of each outer face of
wall and on each side of corners on inner wall
faces. These tension portions shall be provided
with horizontal steel in addition to that required
to reinforce the vertical cantilever effect of walls.
The general arrangement of bars in a rectangular
tank resting on beams is shown in Fig. 11.20.

When the tank is below ground, the dispersion
of steel in the wall depends on the bending
moment diagram for internal water pressure and
external earth /water pressure.

11.5.4.2 Base reinforcement — The bottom
slab of a tank resting on ground shall be doubly
reinforced with horizontal reinforcement at the
top and bottom of the slab. This is required to
cater for the downward pressure when reservoir is
full and upward ground pressure when empty. A
typical reinforcement detail is shown in Fig.
11.21. The use of dowel bars (starter bars) to the
walls shall depend on whether the tank is shallow
or deep.

The main and dis^ibution bars in the base shall
be placed as per slibs. If the walls are high and
long then counterfbrt or buttress walls shall be
used.

11.5.4.3 Roof joint — To avoid the
possibility of sympathetic cracking, it is important
to ensure that movement joints in the roof
correspond with those in walls if roofs and walls
arc monolithic. If, however, provision is made by
means of a sliding joint for movement between
the roof and the wall, correspondence of joints is
not so important.

11,5.5 Circular Tanks — Circular water tanks
are generally analyzed in accordance with
IS c 3370 (Part 4)-I967. This code gives tables for
moment coefficients and shear coefficients for
different end conditions at top and bottom.

11.5.5.1 Wali reinforcement — The
horizontal hoop reinforcement in the circular
tanks are provided either in one layer (for small
tanks) or in two layers (for large tanks). Typical
details are shown in Fig. 11.22.

The spacing of hoop reinforcement is increased
from bottom to top of the wall to allow for
reduction in pressure. Practically it can be varied
at every 1.0 to 1.2 m.

The maximum and minimum spacing of the
hoop steel and the proportions of distribution
steel used will be similar to that of floor slab. The
wall thickness shall be taken as equivalent to the
floor thickness. The laps shall be provided in the
main hoop steel in accordance with Section 4. For
continuity of reinforcement between the base and
the wall diagonal corner reinforcement shall be
provided.

11.5.5.2 Base reinforcement — The base of.
the circular tank shall be doubly reinforced to
resist the downward pressure when full and
upward soil pressure when empty.

The best reinforcement for the base is a square
mesh fabric and this does not require a detailed
plan. When base reinforcement is provided with
corner bars, the details of reinforcement shall be
shown giving details of corner bars (see Fig.
11.23).

It shall be advisable to specify that main bars in
the top layer shall be placed at right angles to

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

173

SP : 34(S&T)-1987

Fig. 11.19 Sketch Showing Deformation of
Rectangulor Tank Under Internal
Pressure

those in the bottom layer and that the position of
overlaps, if required, will be staggered.

11.5.6 Overhead Tanks— Circular and
Intze — A water tower is a typical type of the
overhead tank. The only difference between this
type of tank and one constructed at ground level,
is in the method of support.

11.5.6.1 Roofs — The reservoirs and tanks
shall be provided with roof and will be detailed as
a normal slab supported on beams and columns
or a flat slab supported on columns alone.

In a reservoir that is roofed over, it is possible
that the side walls may not act as a cantilever
wails but as vertical slabs like basement walls.
Then the walls shall be detailed as a slab spanning
vertically between the reservoir base and roof.
Figure 11.24 shows the typical arrangement of
bars (cross-section) in a Intze tank.

11.6 Reinforced Concrete Ifinges — Many
reinforced concrete structures, such as bridges and
portal frames, are designed on the premise that
parts of the structure act as hinges. In very large
structures, the use of a normal metal hinge would
be very expensive and it is, therefore, more
eeonomical to form a hinge using reinforcing
bars. This is possible because the actual rotation
required to satisfy the condition is very small.

11.6.1 Figure 11.25 gives details of three
typical RC hinges used at supports.

174

11.6.1.1 Figure 1I.25A is a type of
reinforced concrete hinge suitable for a large
portal frame or vertical support to a long bridge.
The resilient material placed between the member
and its foundation can be bituminous felt, lead,
rubber or plastic. When the type of hinge is
detailed make sure that the hinge reinforcing bars
are adequately held in place by binders or hoops
as shown. Also the area of concrete marked A is
sufficient to transfer the whole of the compressive
force from the member to the foundation.

The Mesnager hinge showii in Fig. 1 1.25B has a
short portion reduced in cross-section to about
one-third of the width. The narrow concrete
section is heavily reinforced, and provided with
closely spaced binders or hoops. The considered
hinge has spiral reinforcement as shown in Fig.
11.25C. If the section of the hinge is wide then
extra spirals must be detailed. The gap formed
between the abutment and the member is filled
with suitable flexible material.

11,6.2 Crown Hinges — These are inserted
into certain types of arch structures known as
three-hinges, or pinned arches. Figure 11.26 gives
general details for this type of hinge.

In the Mesnager hinge shown in Fig. II.26B,
the main reinforcement crosses at an angle of 60°
and the gap is filled with a waterproof, resilient
material. The joint develops considerable
resistance against thrust and shear, yet has little
resistance to rotation. Figure 1 1 .26C shows a
modification to the Mesnager type of hinge — the
considered hinge. This only acts as a hinge during
the construction of the arch. When the formwork
is removed and the arch drops slightly under its
own action the main reinforcing bars are welded
together and the hinge is concreted in to form a
permanent joint.

11.7 Concrete Pipes — Reinforced cement
concrete pipes are widely used for water mains,
sewers, culverts and in irrigation. When used for
carrying highly acidic sewage or industrial wastes,
necessary precautions shall have to be taken
against chemical attack and corrosion.

Reinforced concrete pipes either spun or cast
shall be designed such that the maximum tensile
stress in the circumferential steel due to the
specified hydrostatic test pressure does not exceed
the limit of 125 N/mm^ in the case of mild steel
rods, 140 N/mm2 in the case of cold-drawn steel
wires and high strength deformed bars/ wires.

The barrel thickness shall be such that under
the specified hydrostatic test pressure, the
maximum tensile stress in concrete when
considered as effective to take stress along with
the te-nsile reinforcement shall not exceed
2N/mm2 but the wall thickness shall not be less
than those given in IS : 458-1971 ^Specification
for precast concrete pipes (with and without
reinforcement {second revision)'.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

iCNimie MOMENT

nsrmeuTioN in

SECTION -A A

•^••****

^ ^^ ■ W

• i > r

s=^

■ ■ ■ ■ » m 9 — ^

, > T-^-T

SECTION'BB

Fig. 11.20 Rectangular Tank Supporting on Beams General Arrangement of
Reinforcement

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

175

SP : 34(S&T)-1987

MAIN STEEL $PANN|N6
SHORTER DIRECTION

LEAN CONCRETE

Fig. 11.21 Rectangular Tank Restrained at Base with Thickening at the base-
Typical Cross Section

MAIN HOOP
STEEL

■A

DISTRIBUTION
STEEL

(MCREASE
SPACING OR
REDUCE
DIAMETER
WITH HEIGHT)

IRCULAR BASE LtEAN CONCRETE

M.22A SECTION THROUGH A CIRCULAR TANK WITH HOOP REINFORCEMENT IN A SINGLE LANGER

DETAILS OF C
BARS ALONG HE

DETAILS OF

MAM BARS
HERE

HALF PLAN

TOP STEEL

DETAILS OF NAIN BARS
PLACED ALONG HERE

IL22B circular SLABS

Fig. 1 1.22 Circular Tank

Fig. 11.23 Typical Arrangement of Bars in a
Circular Base

176

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

OOMIO HOOF

HORIZONTAL TiCS
Al WTtllVAtt TO
MAINTAIN COVCN

LAP LKNaTH
ClAPt

ttAooiRiojn

OMI RAW

11.7.1 Reinforcement — The reinforcement
(circumferential and longitudinal) shall extend
throughout the length of the pipe. The pitch of
the circumferential reinforcement shall be neither
more than 10 cm or four times the thickness of
barrel, whichever is less, nor less than the
maximum size of aggregate plus the diameter of
the bar used. There is no internationally accepted
design method for concrete pipes. Design had to
be based on both practical experience and theory.
Accordingly minimum quantity of steel has been
specified in IS ; 458-1971. All pipes with wall
thickness 75 mm and above shall have double
reinforcement cage and the amount of hoop steel
in the outer cage shall be 75 percent of the mass
of the hoop steel in inner cage.

Note — The ends of concrete pipes shall be suitable
for butt, flush collar, spigot and socket, rebated or
flexible rubber ring joints. All pressure pipes shall
have flexible rubber ring joint. Dimensions of collars
shall be according to IS : 458-1971. The reinforcement
for the collars shall be same as that provided in the
nearest nominal bore of the pipe and the longitudinal
reinforcement shall be proportional to the length of the
collar. The collars shall be spun up to 1200 mm diameter
pipes. Rebated joints shall be used in case of pipes having
wall thickness of 1 10 mm or more.

A typical arrangement of reinforcement is
shown in Fig. 11.27.

Fig. 11.24 Typical ARRANCtMENT of Bars in
A Intze Tank

NoTK Diagonal reinforcement may be provided at 15
percent of longitudinals in pipes for which the cages are
not welded so as to help in binding the cage securely.

MAIN

^RESILIENT REINFORCEMENT ,
MATERIAL

-4- CONFINING
; REINFORCEMENT

CROSSING

MAIN
REINFORCEMENT \ /y^^x,/ /

HINGE BARS

ABUTMENT

HINGE BARS WITH -J

SPIRAL REINFORCEMENT

( CONFINING REINFORCEMENT )

FOUNDATION

Fig. U.25 Reini-orcih Concrete Hinois at SrrpoRis

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIMNt;

17*

SP : 34(S&T>-1987

HEAT CCMEHT AHOUND
BAKS AT CROSSINGS

1I.26A

BARS WEIOCO AND OPCNINO
CONCRETED UP AFTER FQRM«><QRtC
STRUCK

WITH KEUCAL REINFT.

II.26B

il.26C

Fig. 11.26 Crown Hinges

11.7.2 Cover — Clear cover to any
reinforcement should not normally be less than
the following:

Barrel Thickness

Up to and including 25

Over 25 up to and including 30

Over 30 up to and including 75

Over 75

As spigot steps

Nominal
Clear Cover

8
10
15

Note — For class NP4 pipes (in accordance with IS:
458-1978, the minimum cover shall be 20 mm,

11.8 Machine Foundations

11.8.1 Foundations for Impact Type machines
(Hammer Foundations) [IS : 2974 (Part 2)-l980
'Code of Practice for Design and Construction of
Machine Foundations: Part 2 Foundations for
Impact Type MachinesiSccond Revision)^— The
foundation block should be made of reinforced
concrete. It is desirable to cast the entire
foundation biock in one operation. If a
construction joint is unavoidable, the plane of the
joint shall be horizontal and measures shall be

taken to provide a proper joint. The following
measures are recommended:

Dowels of 12 or 16 mm diameter should be
embedded at 60 mm centres to a depth of at
least 300 mm at both sides of the joint. Before
placing the next layer of concrete, the
previously laid surface should be roughened,
thoroughly cleaned, washed by a jet of water
and then covered by a layer of rich I : 2 cement
grout (1 cement : 2 sand), 2 cm thick. Concrete
should be placed not later than 2 hours after
the grout is laid.

11.8.1.1 Reinforcement shall be placed
along the three axis and also diagonally to
prevent shear failure (see Fig. 11.28), Additional
reinforcement shall be provided at the top side of
the foundation block than at the other sides.
Reinforcem.ent at the top m.ay be provided in the
form of layers of grills made of 16 mm diameter
bars suitably placed to allow easy pouring of
concrete. The topmost layers of reinforcement
shall be provided with a cover of at least 5 cm.
The reinforcement provided shall be at least 25
kg/m^ of concrete.

Figure 1 1.28 shows typical reinforcement details
of a hammer foundation block.

178

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&TM987

r>ioo

rPITCH<>«

t<7S

SECTION AA

n.27A SINGLE LAYER

^*f

— T)' " g^Hpng u ^'^

ir WW

" " " Hsftadaa

Tf ■ g" o p

• g tf ' " w q T y

A— «^

DETAIL AT X

SECTION AA

FIXING TIES
AT SUITABLE
INTERVALS TO KEEP
THE CAGE IN POSITION

1I.27B DOUBLE LAYER

Fig. 11.27 Typical Details of Pipes

11.8,2 Foundations for Rotary Type Machines base slab, 70 kg/m^ of concrete for columns and

of Low Frequency [IS : 2974(Part 4)'1979] — lht 90 kg/m^ of concrete for top slab,
amount of minimum reinforcement for block
foundation shall be 25 kg/m^ of concrete. The

amount of minimum reinforcement for frame Stirrups suitably spaced shall be provided to tie

foundations shall be 40 kg/m^ of concrete for together the main longitudinal bars.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

179

SP : 34(S&T)-1987

CUT-IN

/-ELASTIC
/ LAYER

^FOUNOATION BLOCK

Fig. 1 1.28 Typical Reinforcement Detail

The minimum diameter of the mild steel bars
shall be 12 mm and the maximum spacing shall be
200 mm.

The concrete cover for protection of
reinforcement shall lie 75 mm at the bottom, 50
mm on sides and 40 mm at the top.

Typical arrangement of reinforcements are
shown in Fig. 11.29 to 11.31.

11.8.3 Foundations for Reciprocating Type
Machines [IS : 2974 (Part iyi982].

11.8.3.1 Minimum reinforcement in block
foundations — Minimum remforcement in the
concrete block shall be not less than 25 kg/m^
For machines requiring special design
considerations of foundations, like machines
pumping explosive gases, the reinforcement shall
be not less than 40 kg/m^.

The minimum reinforcement in the block shall
usually consist of 12 mm bars spaced at 200/250
mm centre-to-centre extending both vertically and
horizontally near all the faces of the foundation
block.

11.8.3.2 The following points shall be
considered while arranging the reinforcements:

a) The ends of mild steel (if used) shall always
be hooked irrespective of whether they are
designed for^ tension or compression;

b) Reinforcement shall be used at all faces;

c) If the height of foundation block exceeds
one metre, shrinkage reinforcement shall be
placed at suitable spacing ^n all three direc-
tions; and

d) Reinforcement shall be provided around all
pits and openings and shall be equivalent to
0.50 to 0.75 percent of the cross-sectional
area of the opening.

11.8.4 Foundations for Rotary Type
Machines (Medium and High Frequency)
[IS: 2974 (Part 3)-1975 'Code of Practice for
Design and Construction of Machine
Foundations: Part 3 Foundation for Rotary Type
of Machines {Medium and High Frequency)
(First Revision)].

11.8.4.1 The vertical reinforcing bars of the
column shall have sufficient embedment in the
base slab to develop the required stresses.

11.8.4.2 All units of foundation shall be
provided with double reinforcement.
Reinforcements shall be provided along the other
two sides of cross-sections of beams and columns,
even if they are not required by design
calcinations so that symmetric reinforcement will
be ensured in opposite sides.

11.8.4.3 The amount of minimum rein-
forcement for major structures components of the
framework shall be as follows:

a) Base slab

b) Columns

c) Top table

(slab and beam)

40 kg/m^ of concrete
70 kg/m-* of concrete
90 kg/m^ of concrete

Typical arrangement of reinforcement is shown
in Fig, 11.33.

11.8.4.4 Stirrups suitably spaced shall be
provided to account for the entire shear in the
foundation elements.

11.8.4.5 The minimum diameter of
longitudinal steel for beams and columns should
be selected so that the maximum spacing of these
bars shall not be more than 150 mm.

11.8.4.6 Reinforcement cover — Unless
specified otherwise, the concrete cover for
reinforcement protection shall be as follows:

a) Base slab

b) Columns and

pedestals

c) Beams

100 mm for top,
bottom and sides

50 mm on sides

40 mm on sides

11.8.4.7 Minimum grade of concrete for
foundation shall be not Tcss than M20.

11.8.4.8 Construction joints — The base
slab shall be cast in a single pour. A properly
designed construction joint shall be provided
between the base slab and the columns.

Wherever intermediate decks exist and
construction joints are to be provided, the
subsequent set of construction joints shall be
provided at the top of each such intermediate
deck.-

A typical arrangement of reinforcement in a In case there is no intermediate deck,
reciprocating machine foundation is shown in continuous concreting shall be done for the
Fig. 11.32. columns and the upper deck.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

[

i i i ■ ■ ^
t t4> ■ • i

i i i ^

MMM^Mmmmmm m%^ m i

SECTION -AA

A • *--**••*•***• *

"V" j

"^^

'*'"

""*

*" *

.a^ t

k J

^^j

k t

"■

^ ►

A J

h""^

-- •—

U-

► ^
1 *

> 1

►

f-;

►

•

(

SECTION -B

Fic

}. 11,29

SECTION -CC

11.9 Shear WaHs — In tall buildings, rather than
relaying on columns alone for resisting moments
due to lateral forces, it is common practice to
provide a core of shear walls to take major part of
lateral force against the building. Figure 11.32
shows the structural effects on the wall, and since
the wind can act in either direction, compression
bands occur at both ends of the wall.

The general principal being the cross-sectional
area of the concrete alone must resist the shear
forces imposed at joints with the slab whilst the
remainder acts like a beam on edge spanning
between floors.

Reinforcement in the cornpression band must
be tied in two directions as in the case of column
bars and compression beam steel.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

181

SP : 34(S&T)-1987

•SQ POCKET FOR
ANCHOR eOLT

1 OF OIL

DRAIN

OF PULVERIZER
UNIT

TOP OF STRUCTURAL
STEEL

CIRCULAR BINDERS
RADIAL BAR

FLOOR

. .

► '

!*.*•■

•■

■ ,' »

• •.

.-".-•rl

'. ••

-REINFORCEMENT
BARS

"TOP OF
CONCRETE
RAFT

SAND FILLING

SECTION XX
(CONCRETE NOT SHOWN)

Fig. 1 1.30 Typical Foundation for Crusting Mill (Pulverizer Unit)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNG

SP : 34(S&T)-1987

t OF DISCHAROC OF PRIMARY
AIR FAN UNIT

•t OF PRIMARY AIR
FAN FOUNDATION

COVERED TRENCH

GROUT — I

/ JMS . at WMr . fr -r** — * — — H — 1 =

/ ft" • ' ■ ' 1L_-_ ,.

REINFORCEMENT
BARS

SECTION XX

{CONCRETE NOT SHOWNi

Fig. 11.31 Typical Foundation for Prinary Air Fan

}

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

1S3

SP : 34(S&T)-1987

[4 HOLES fOR MOTOR FOUNDKHON
80US WITH SQUARE PLATES

4 HQtES FOR COMPRESSOR
FOUNDATION BOLTS
WITH SQUARE PLATES

^t OF FOUNDATION
OROUr

BMOERS

THROUGH

u//i Dph □

C OF MOTOR

^t OF compressor\

'T,

REMFORCEMENT BAR
ALL ROUND

,-4

GROUT

DOWEL
ROUND

TOP OF RAFT

FWISHED GROUND FLOOR
TOP OF CONCRETE

=^T=!=?|

!>n3

# ..M

V U •M-

LllJL-J

■ LI- J

REDUCED SECTION YY
(CONCRETE NOT SHOWN)

SECTION XX
Fig. 1 1.32 Typical Foundation for Instrument Air Compressor

TOP lAVCR OF KAM
•ARS MTD COUJMN

SAME NUMaen and see

AS INTERRUPTED

^*] /-TURaMe-6e.<4eflAim

SHMMG JUNCtlON
OF COLUMN AND

II.33A TYPICAL LONGITUDINAL SECTION THROUGH A TURBO GENERATOR FOUNDATION

Fig. 11.33 Typical Details of a Turbo Generator Foundation (Commuted)

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

TURBINE-GENERATOR
BASE UNE

r MACHINE BASE

TURBINE-GENERATOR (gNLARGED SECTION \ ^ MACiUNe BASE

BASE UNE

FINISH

'^''

•

-':-ll

•

•i* -

• *

r-r^

■ * ■

. *

- '* '

•■}--l;>l

i-;l;i

ENLARGED SECTJON OD

ENLARGED SECTION BB

■*■ *•

.*•

^ " *•.■

«-.'.*■•

* • ."

»;■

,4; «•

; -. .

■:;• 1

* ' -^

rf .

■ «■■•

■ ■ • • .

•' 1 . '

«k .^•.-■

• «•

• • ♦.'*

. ,

•- A-

I'- . . •

• ,

# • ■ •

". *. ■

..■'•■

.; *

* • '■ * *L ' '■'.

«:^

^-^— —

- *.

ENLARGED SECTION EE

ENLARGED SECTION CC

^..,o II lor TYPirAl REINFORCEMENT OF COLUMNS

I1.33B TYPICAL REINFORCEMENT OF BEAMS n.32C TYPICAL Ktmrv^^^

Fig. 1 1.33 Typical Details of a Turbo Generator Foundation

HANDBOOK ON CONCRETE Ri:iNFORCEMENT AND DETAILING

185

As in the Original Standard, this Page is Intentionally Left Blank

SECTION 12
Ductility Requirements of Earthquake Resistant Buildings

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

SECTION 12
DUCTILITY REQUIREMENTS OF EARTHQUAKE RESISTANT BUILDINGS

12.0 General — The primary members of struc-
ture such as beams and columns are subjected to
stress reversals from earthquake loads. The
reinforcement provided shall cater to the needs of
reversal of moments in beams and columns, and
at their junctions.

Earthquake motion often induces forces large
enough to cause inelastic deformations in the
structure. If the structure is brittle, sudden failure
could occur. But if the structure is made to
behave ductile, it will be able to sustain the
earthquake effects better with some deflection
(Am) larger than the yield deflection (Ay) by
absorption of energy. Therefore, besides the
design for strength of the frame, ductility is also
required as an essential element for safety from
sudden collapse during severe shocks. It has also
been observed during past earthquakes that
structures designed and built for low seismic
coefficients survived severe earthquakes with little
damage because of energy absorption in plastic
deformations.

In zones where risk of major damage from
earthquake loads is possible, ductile frame is
required in accordance with IS : 4326-1976 *Code
of practice for earthquake resistant design and
construction of buildings (first revision)*. These
provisions are generally applicable to all seismic
zones but its importance is greater where severe
earthquake loadings will become much more
significant than other concurrent loads.
Accordingly the Code makes it obligatory that in
all cases where the design seismic coefficient [see
IS : 1893-1976 ^Criteria for earthquake resistant
design of structures (third revision)*] is 0.05 or
more (which invariably includes zones IV and V)
ductility provisions specified in IS : 4326-1976
shall be adopted. The ductility requirements will
be deemed to be satisfied if the conditions given in
the following clauses are achieved.

12.1 Flexural Members

12.1.1 The top as well as bottom steel
reinforcement shall consist of at least two bars
each throughout the length of the member, and
the steel ratio p on either face (both on
compression and tension face) shall not be less
than as given below:

For M 15 concrete and plain mild steel bars,
pmin = 0.003 5

For other concrete and steel reinforcement, pn^n
= 0.06 FJFy

where

p = AJbd,

Fc = 28-day cube crushing strength of concrete,
Fy = yield stress of reinforcing steel,
A^ = area of steel on a face,

b == breadth of beam web, and

d = effective depth of section.

12.1.2 The maximum tensile steel ratio on any
face at any section shall not exceed the following:

For M 15 concrete and plain mild steel bars,

Pm.x = Pc + 0.011

For other concrete and mild steel reinforce-
ment, p max - pc + 0.19 FcIFy

For concrete reinforced with coldworked
deformed bars, Pimx = pc + 0.15 FJ Fy

where

Pc = actual steel ratio on the compression face.

12.1.3 When a beam frames into a column,
both the top and bottom bars of the beam shall be
anchored into the column so as to develop their
full tensile strength in bond beyond the section of
the beam at the face of the column. Where beams
exist on both sides of the column, both face bars
of beams shall be taken continuously through the
column.

Note — To avoid congestion of steel in a column in which
the beam frames on one side only, it will be preferable to use
U-type of bars spliced outside the column instead of
anchoring the bars in the column.

Figure 12.1 shows the typical detail for a beam
framing into column from one side or two sides.
Such an arrangement will ensure a ductile
junction and provide adequate anchorage of beam
reinforcement into columns. Top and bottom
longitudinal steel for beams framing into both
sides of column should extend through the
column without splicing.

12.1.4 The tensile steel bars shall not be
spliced at sections of maximum tension and the
splice shall be contained within at least two closed
stirrups (see Fig. 12.2).

12.1.5 The web reinforcement in the form of
vertical stirrups shall be provided so as to develop
the vertical shears resulting from all ultimate
vertical loads acting on the beam plus those which

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

189

SP : 34(S&T)-1987

CONTINUOUS BARS NOT IISS THAN 1/. ARCA
OP BARS AT COLUMN FACE ^^

Designer should provide dimension A^ S^ d, anchorage length, cutoff points of discontinuous bars,
^provide not less than two stirrups throughout splice length.

A ~ distance to point of inflection plus anchorage length but not less than IJi. Designer may cut some
ban shorter than this but at least one-third the area of bars at the face of column must extend this
distance
d = Effective' depth of beam
IH ~ Internal radius = 4 di, minimum, 6 dy, preferable
Li ~ development length
<4 ~ diameter of bar

Fig. 12.1 Example of Typical Bar Details for Special Ductile Moment resisting
Frames (Column Details Excluded)

Fig. 12.2 Closed Stirrups

h IF SINGLE LOOP

„ h ff DOUBLE.
' LOOP

h IF INTERMEDIATE
TIE USED

LARGER

maximum shear carrying capacity will be
restricted below 50 percent of the design shear.
Closely spaced stirrups are preferable.

12.2 Columns. Subjected to Axial Load and
Bending

12.2.1 If the average axial stress PjA on the
column under earthquake condition is less than
0. 1 Fc, the column reinforcement will be designed
according to requirements of flexural members
given in 12.1. But if PjA^QA /%=, special
confming reinforcement will be required at the
column ends as given in 12.2.2 to 12.2.4.

12.2.2 The cross-sectional area of the bar
forming circular hoops or a spiral used for
confinement of concrete will be :

«°«^^t(l-')

INTERMEDIATE TIE

where

Fig. 12.3 Dimension h in Rectangular Hoop /tsh = area of bar cross-section.

can be produced by the plastic moment capacities
at the ends of the beam. The spacings of the
stirrups shall not exceed £//4 in a length equal to
Id near each end of the beam and djl in the
remaining length (see Fig. 12.1). It is important to
note that in no case shear failure should preceed
flexural failure.

12.1.6 Because of the possibility of reversal of
shears in the beams, the earthquake shears shall
be provided for by the vertical stirrups as they will
be effective both for upward and downword
shears. Where diagonal bars are also used, their

s = pitch of spiral or spacing of hoops,

Ac = diameter of core measured to the outside
of the spiral or hoop,

Fc = 28-day cube crushing strength of concrete,

Fy — yield stress of reinforcing steel
(hoop or stirrups),

A = gross concrete area of the column
section, and

Av = area of core

190

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

In the case of rectangular closed stirrups used
in rectangular sections, the area of bar shall be:

Ash = 0A6 s

where

h = longer dimension of the rectangular con-
fining stirrup, and

Ay - area of confined concrete core in the
rectangular stirrup measured to its out-
side dimensions.

Note — The dimension h of the siirrup could be reduced
by introducing links at intermediate points as shown in
Fig. 12.3. In this case also At shall be measured as overall
core area regardless of the stirrup arrangement. Each end of
the intermediate tie shall engage the periphery hoop with
a standard semicircular hook and shall be secured to a
longitudinal bar to prevent displacement of the intermediate
tie during construction.

12.2.3 The special confining steel, where
required, shall be provided above and below the
beam connections in a length of the column at
each end which shall be the largest of:

a) 1/6 of clear height of the column,

b) larger lateral dimension of the column, and

c) 450 mm.

The spacing of the hoops or closed stirrups
used as special confming steel shall not exceed
10 cm Xsee Fig. 12.4 and 12.5).

12.2.4 Shear reinforcement shall be provided
in the columns to resist the shear resulting from
the lateral ana vertical loads at ultimate load
condition of the frame. The s peeing of shear
reinforcement shall not exceed d\ 2, where d is the
effective depth of column measured from
compression fibre to the tension steel.

12.3 Beam-Column Connectiosis — Joints
between exterior columns and adjoining flexural
members shall be confined by transverse column
reinforcement through the joint. Such
reinforcement shall consist of circular hoops or
spiral in the case of circular columns and
rectangular closed stirrups in the case of
rectangular columns, as required at the column
ends. This is required because on exterior or
corner columns the joint core is not confined by
flexural members on all sides. To provide some
measure of confinement in these situations giving
some strength against brittle failure in the joint
core, transverse reinforcement as required at the
column ends is continued through the joint core
{see Fig. 12.4 and 12.5).

The transverse reinforcement is required at the
end of the column even if the column is confined

END REGION ( S«« Clause 12-2-3)
BEAM

COLUMN C

ORE*

END REGION { S»« CUutt 12-2-3 )

SPACING OP LATERAL TlES:f |

'^'column core HAS TO BE CONFINED
BY CIRCULAR OR RECTANGULAR TIES

IN ACCORDANCE WITH END REGION

COLUMN

Fig. 12.4 Beam Column Joint at External Columns

HANDBOOK ON CONCRETE REINFORCEMENT aND DETAILING

191

SP : 34(S&T)-1987

by beams from all four sides. The amount of
transverse reinforcement in this case may be
reduced to half the value. The tie reinforcement at
beam-column joints may be provided by U-

shaped ites (hair pin type), the length of the legs
beyond the columns being kept is dictated by
bond requirements so as to develop full strength
of the tie {see Section 7).

END RCaiOH KM OR OR
iSOmm WHICHEVER IS
ORCATER

,— SMCINS IN END REOION
lOOintit fMK.

'1-

END REOKW

i_i

FIRST STIRRUP Wmm PROM
•CAM FACE

SMCINO AS PER
»UT:^d/2

b o>b

SECTION AA

Fig. 12.5 Spacing of Shear Reinforcement in Columns

192

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SECTION 13

Transport, Storage, Fabrication, Assembly and
Placing of Steel Reinforcement

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

SECTION 13

TRANSPORT, STORAGE, FABRICATION, ASSEMBLY AND PLACING OF STEEL

REINFORCEMENT

13.1 Transport and Storage

134.1 Transport — This clause only concerns
the transport of unshaped reinforcement.
Reinforcement is to be protected during loading,
unloading and transport. The following shall be
avoided:

a) Accidental damage or notches causing a
decrease in section.

b) Contact with other products liable to
deteriorate or to weaken the bonding of the
reinforcement.

c) Any permanent bends in the reinforce-
ment, straightening being unadvisable.

d) Removal of any anti-corrosive protection
present.

Care should be taken not to destroy the marking
or labelling of the products. In order to facilitate
any subsequent handling (unloading, distribution
in the stock), batches of identical reinforcement
should be grouped during transport.

13.1.1.1 Transport between the supplier
and the consumer — Tt&mport is generally by
road. Wherever possible good accessibility to
bundles of reinforcement should be maintained to
allow rapid handling (separation timbers, slings).
Unloading should be carried out mechanically
wherever possible.

134.1.2 Transport on the fabrication
area — The operation is generally expensive.
However, rationalization and industrialization
may lead to greater mass production which allows
better use of mechanical lifting methods and
reduces reliance on manual transport. Transport
between various shaping machines may be carried
out on tables fitted with rollers; these tables may
be mobile and thus serve several production lines.
Transport by lifting necessitates the use of a hoist
fitted with several attachments for holding the
bundle and preventing any permanent
deformation in the reinforcement.

13.1.2 Storage — Dnring storage, the
reinforcement elements should be carefully
indexed and classified according to their diameter,
type^ grades, length and batch of origin.

When the design of ribs or the distribution of
the marking allows easy identification even for cut
lengths, accidental substitution is not frequent; on
the other hand, there is danger of confusion for
^laifl reinforcement without markings or with

markings which are not repeated. It is thus
necessary to use the entire length of the
reinforcement or the cut reinforcement bearing
the distinctive mark last of all. The cleanness of
the steel without stains, such as grease, oil, paint,
earth, non-adherent rust or any other substance
which is harmful to its good preservation and
bonding is important. The whole of protective
coating, if any, shall be protected during storage
and steel-fixing. When the reinforcement is
removed from store, the surface state should be
examined to ensure that the steel has not
undergone any harmful deterioration. If the
design engineer considers it necessary, the
manufacturer (or the fabricator) shall carry out
quality control tests.

This examination should be all the more
detailed the longer the storage period, the more
severe the environmental conditions, and
higher the grade of steel.

Both on site (as far as possible) and in the
works, a sufficient storge area should be provided
to facilitate handling to prevent any error or
confusion.

The storage area shall provide free access for
the arrival of unbent reinforcement and be close
to the measuring tables and other bending
equipment. When a fabrication post is set up on
site, but mainly during the design of larger
reinforced units, any handling which is not strictly
necessary shall be avoided wherever possible. As
commercial lengths are large, any rotation of the
reinforcement in a horizontal plane shall be
excluded. This is possible when the reinforcement
is stored in alignment or parallel to the measuring
tables and the cutting tables.

13.2 Cutting — The reinforcement is cut in
accordance with the cutting schedules. Cutting is
carried out with the aid of shears power-operated
or otherwise taking care not to damage the ribs in
the neighbourhood of the sheared section.

Flame cutting and electrode cutting is not
advised for reinforcement other than that in mild
steel. It may alter the properties of heat-treated
steel over a small length (a few diameters).

The cut lengths are generally measured on a
measuring table; this ensures that flatness and
straightness of the reinforcement are checked
during measuring and the tolerances are complied
with more easily.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

195

SP : 34<S&T)-i987

For repetitive series, that is generally in
factories, measuring tables are fitted with
detachable stops, fixtd in advance by the operator
to obtain the desired lengths for several
reinforcing bars simultaneously. Reinforcement
on these measuring benches is transported by
means of rollers, in some cases power-driven or
by winches.

Tolerances on cut lengths depend on the
tolerances for:

a) the concrete cover to the reinforcement,

b) the position of the reinforcement, and

c) the structural element (shuttering).

Other tolerances may be imposed by special
conditions:

a)" orthogonality of the sheared section in
relation to the axis of the reinforce-
ment (flash welding, sleeve splice), and

b) absence of burns^ (sleeve splice).

Depending on the criteria of use, one may
prefer one piece of cutting equipment to another
(cutting by shears, cutting by power saw, etc).

13.3 Fabrication

13.3.1 G^wera/— Fabrication involves
shaping of the reinforcement elements, that is,
bending and radiusing (that is, bending with a
large radius of curvature).

Fabrication is carried out in accordance with
the schedules. The schedules shall be followed as
strictly as possible; in fact, straightening is always
hazardous, systematic rebending should,
therefore, be avoided. It is advisable, if the
bending has to be corrected in-situ, for this
operation to be carried out by accentuating the
bending rather than by straightening.

During fabrication, consideration shall be given
to the fact that due to the elastic return of a bent
bar, the real angle may (as function of the grade
and diameter) be greater than the angle of
rotation of the plate. The operator should
therefore, overbend.

The minimum diameter of the mandrel shall be
at least equal to the minimum diameter of the
bending-rebending test specified in the
Agreement, and shall be selected so as to avoid
crushing or splitting of the concrete under the
effect of the pressure which is exerted inside the
curve.

For anchor hooks at the ends of the
longitudinal bars, the minimum diam.eter of the
mandrel shall never be less than 5 <^. The
fabricator shall ensure the quality of bending
(absence of cracks, etc) by a visual examination.

In general, tolerances are not fixed on bending
angles; on the other hand, it is important that the

overall dimensions of the fabricated reinforcement
conform to the plan (correct placing, sufficient
concrete cover, etc).

The bending speed depends on the nature of the
steels and the am.binet temperature: it shall be the
subject of a preliminary experimental
determination if it is not fixed in the Agreement
or by the regulations.

Bending and radiusing, which are similar
operations, are carried out cold. The use of a
torch to facilitate this operation is generally
prohibited, since it can, for example, alter the
mechanical properties of cold worked steel.

Fabrication, even when mechanized, requires
many operations: its relative importance in the
overall cost of reinforcement is high.
Rationalization of these operations and use to the
greatest possible extent of rectilinear
reinforcement are essential in order to reduce the
overall cost.

13.3,2 Equipment — Bending of bars may be
done either by improvised means or by hand*
operated machines {see Fig. 13.1, 13.2 and 13.3)
and by power-operated bender. Foe bars of 12
mm diameter and under, m.echanical contrivances
of the type illustrated in Fig. 13.1 may be
advantageously employed.

13.3.2.1 Two of the most common types of
bar-bending machines suitable for bending bars
cold are shown in Fig. 13.2 and 13.3. The essential
components_of the machines are also illustrated in
the figures. The hand machine shown in hig. 13.2
could be employed for bending bars up to 16 mm
diameter and for larger diameters geared bar
bender shown in Fig. 13.3 is required. Special
roller spindles may be necessary for bending
deformed and twisted bafs.

13.3.2.2 Bending of bars of 36 m.m. diameter
am' larger require special equipment, such as

MANDREL

stop-
Fig. 13.1 Bending of Bar by Means of Claw

196

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

SOCKET

HOLE

MANDREL

Fig. 13.2 Simple Bar-Bending. Machine

HOLE

MANDREL

RATCHET LEVER

PLAIN ROLLER

SPINDLE
^ GROOVED ROLLER

Fig. 13.3 Geared Bar-Bending Machine

power-operated benders. However, where only a
few bars are to be bent, easy bends may be
formed by jimcrow or rail bender, an appliance
comprising forged bow with a steel square
threaded screw.

13.3.2.3 Where large quantities of bars are
to be bent, power-operated benders may be
advantageously used.

13.3.2.4 Operation — The hand-operated
benders are generally mounted on tables. Various
operations irivolved and the schematic way of
bending are illustrated in Fig. 13.4. The bar to be
bent should be placed between two stops driven
into a steel or wooden table. The bar should be
held rigid at one of the stops by a roller sitting
over the mandrel. By using a tommy bar and
levering, the bar may be bent to the desired angle.

13.3.2.5 Special patented appliances for
bending bars into helical, rectangular and other
shapes are available and they may also be used.

13.3.3 Bending and Cutting Tolerances —
Where an overall or an internal dimension of the
bent bar is specified, the tolerance, unless
otherwise stated, should be as follows:

Dimension

Tolerance

For bent

^75

+ 3

bars

- 5

> 75 < 150

+ 5
-10

> 150 < 250

+ 6
-15

>250

+ 7
-25

For straight
bars

All lengths

+ 25
-25

13.3.3,1 Any excess in length of bar
supplied over the total of lengths of the various
portions of the bar between bends, including the
specified tolerances or not, shall be taken up in
the end anchorages, or in that portion of the bar
which shall be indicated on the schedule. The
cutting lengths shall be specified to the next
greater whole 25 mm of the sum of the bending
dimensions and allowance.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

197

SP : 34(S&T)-198'

ROLLER

BODY OF MACHINE
MANDREL

CENTRE

ROLLER-^ ^STOP

CENTRE OF BAR TO START OF BEND

STPAIGHT EDGE

TO OBTAIN ANY DEPTH OF SET
PLACE BAR TOUCHING STOP
AND MANDREL. MEASURE THE
REQUIRED DISTANCE FROM A TO B

TO OBTAIN DESIRED DISTANCE FROM
BEND C TO INSIDE OF HOOK D,
MEASURE FROM OPEN SET C TO FAR
SIDE OF MANDREL D. FOR OVERALL
MEASUREMENT ADD THICKNESS OF BAR

\=3

BENT BAR

Fig. 13.4 Bending of Bar

13.3.3.2 The cutting tolerance for bars to be
bent shall be the tolerance given for straight bars.
To allow for this cutting tolerance when
dimensioning bent bars, at least one dimension
shall not be specified.

13.4 Assembly and Placing of the Reinforce-
ment Elements

13.4.1 General — This section covers the
partial or total (flat or spatial) assembly, in
accordance with the reinforcement drawings, of
the reinforcement elements. This assembly may be
carried out:

a) at the works,

b) at the fabrication location on site, and

c) at the immediate position of the component,
that is:

1) in the shuttering,

2) above the shuttering, and

3) outside the shuttering.

If assembly is not carried out at the spot where
it is to be positioned, the accuracy of the assembly
shall be closely monitored. Depending on the
assembly point and subsequent handling,
various precautions have to be observed:

a) conformity to the schedules, respect of
tolerances imposed, respect of spacing, cover
and lapping of the bars;

b) invariability of the position of the bars,
rigidity of the whole; and

c) possibility of placing and compacting the
concrete (with a vibrating poker in many
cases).

These problems shall be taken into account
from the design stage onwards.

These conditions can be satisfied by well-
thought out design and careful assembly.

For assembly outside the shuttering, the fixer
uses gauges, trestles and special temporary
wooden supports (or steel in the works). These

198

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

devices can sometimes consists of auxiliary
reinforcing bars which do not play a part in
carrying stresses. The placing of these bars shall
conform to the various regulations concerning the
concrete cover, distance between bars, etc.

In addition some auxiliary bars are, if
necessary, planned to prevent large deformations
in the reinforced and assembled structures.
Handling of prefabricated reinforcement requires
some care: any accidental displacement of a bar
or any permanent deformation should be avoided.

In some cases, and in particular for large
reinforced structures, hoisting equipment is fitted
with a spreader bar hooked in several places to
the element to be positioned (see Fig. 13.5).
Assembly may involve cases where only partial
assembly can be carried out since the weight to be
lifted and/ or the accessibility of the shuttering
and the possibility of making satisfactory joints
inside the formwprk act as limits.

- SPREADER
BAR

y^HOOKt-^

1. Bridle 2. Spreader Bar 3. Hooks

Fig. 13.5 Hoisting Equipment

The various assembly operations shall take
account of the presence of elements such as
recesses and service pipes and conduits, etc,
embedded in the concrete of the structural
element.

Prefabricated reinforcement is fixed with ties,
couplers, welds or carefully arranged supports, of
suitable solidity and in sufficient number so that
they can be neither displaced nor deformed during
placing of the concrete or during transport and
placing of the reinforcement structure when it is
assembled outside the shuttering.

The cost of reinforcement may be broken down
as follows:

— raw materials

— production

— design costs — calculations

— drawings

— preparing schedules

— checking

HANDBOOK ON CONCRETE REINFORCEMENT AND

CostW

Production costs (cutting, bending, transport,
assembly and fixing) may vary depending on the
product, preparation, design of the reinforcement,
from 4 to 5 manhours per tonne to 150 manhours
per tonne.

Exampfes

Reinforcement of a Beam or Column (Outside
the Shuttering).

Cut and bent bars are stored nearby, sorted and
collected into bundles and labelled (these have
been produced either on site, or delivered cut and
bent by a reinforcement factory).

The fixer puts longitudinal bars on chair
supports (minimum 2 chairs). The position for
stirrups is measured and marked off. Each stirrup
by being moved slightly apart is introduced
around the bars. Angle bars are tied with a double
knot to the main upper bars. By separating
slightly either the chair, or the bars, the lower
bars are brought down; these are held by the
stirrups. The necessary intersections are tied up.
In some cases, dowel bars are introduced at the
ends of the cage. Removal of the whole after
labelling (if not to be used immediately).

Reinforcement of a Slab :

— marking off in chalk the distances between
axes;

— placing of the main bars;

— placing of the secondary reinforcement;

— tying of intersections;

— placing of the spacers for the lower bed;

— placing of spacers between two layers;

— placing of the distribution reinforcement on
the spacers, and other secondary reinforce-
ment on the lower bed;

— placing of the main reinforcement; and

— lifting of the secondary reinforcement and
tying.

Reinforcement of a Wall — In general, the wall
remains accessible from at least one side: rein-
forcement starts on the other:

— fixing of vertical bars to the dowel bars and
the spacers;

— positioning and tying of horizontal bars;

— positioning of the horizontal dowel bars for
the front bed;

— fixing of vertical bars and tying in horizon-
tal bars lifted as needed; and

— placing of spacers between the two vertical
layers.

Assembly of Prefabricated Reinforcement —
Apart from the problem of deformability during
transport and handling, assembly is carried out in
the same way as above, but at the works. Fixing is
carried out by welding or tying. Units are limited
by the lifting capacity available on site and the
maximum dimensions authorised for the means of
transport anticipated.

The reinforcement factory decides on the
method of jointing reinforcement structures

DETAILING

199

SP : 34(S&T)-1987

(independent bars to be drawn from the cages,
welding or mechanical coupling methods, etc).

13.4.2 Fixing — As regards assembly on site,
bars which touch while crossing are fixed
generally by very tight annealed wire ties of I to 2
mm, or sometimes by some special device.

13.4.2.1 r>'m^ — Tying may, in order of
increasing resistance to slipping, be by means of a:

— single or snap tie (see Fig. 13.6)

— saddle ties

— figure of eight tie

n::>x=2 cgi

SINGLE

SADDLE

Fig. 13.6

FIGURES

Recourse to stronger ties may enable the
number of nodes tied to be limited. It is, in any
event, recommended that the direction of single
knots be alternated so as to increase the rigidity of
the mesh {see Fig. 13.7).

Fig. 13.7 Alternated Tying

The need to tie a certain percentage of the
nodes depends not only on the type of tie used,
but also on the diameter of the bars, their surface
shape (smooth or notched) and the rigidity which
one wishes to give to the reinforcement (handling,
transport, etc).

Tying wire is delivered in small coils.

Pieces of wire with two eyelets are also used,
tied with the aid of special pliers with a hook.
This method is faster with an unskilled workforce
(see Fig. 13.8).

With skilled fixers tying is the best method of
jointing on site.

m0^

The bottom of the shuttering must be cleared of
any wire waste before concreting Ho prevent it
causing rust stains and corrosion paths on the
surface from which the shuttering is to be
removed. For this purpose a magnet suspended at
the end of a chain which is taken along the
bottom of the shuttering, or even a jet of
compressed air, may be used.

13.4.3 Placing the Reinforcement — Correct
placing of reinforcement requires proper
maintainance of the distances between bars, and
concrete cover, that is, the exact placing of the
reinforcement in accordance with the drawings.

This is, in general, achieved by using spacers to
ensure that the reinforcement is kept in the
position allocated in the design, resisting the
actions to which it is subjected during placing.
The parts of spacers in contact with the shuttering
shall resist corrosion and shall not affect the
appearance of the concrete when the shuttering is
removed. When the concrete has hardened they
shall not cause cracking or infiltration of water,
which causes corrosion.

13.4.3.1 Distance between parallel rein-
forcement elements:

a) Between horizontal layers — The distance
between these layers is often ensured by
means of a bar (say 12 mm diameter) bent as
shown in Fig. 13.9.

Fig. 13.8 Prefabricated Fixing Wire

Fig. 13.9 Layer Spacers

This high chair, which is easy to make on
site, is fixed to the main reinforcement and
is never in direct contact with the shuttering.

Prefabricated devices such as those
indicated in Fig. 13.10 are also used, either
for isolated bars (bar chairs), or for heavy
layers (continuous chairs and bolsters).

b) Between vertical layers — The distance
between vertical layers of reinforcement (see
Fig. 13.11) is usually ensured by means of
straight bars, hooked bars or bars bent into,
a U, tied to the main reinforcement.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&TM987

$HUTTERtN6

I3.iOA FOR ISOLATED BARS (HIGH CHAIRS)

13.10B FOR HEAVY LAYERS (CONTINUOUS CHAIRS)

Fig. 13.10 Chairs

U-BAR

HOOKED BAR

STRAIGHT BAR

Fig. 13.n Spacers for Vertical Layers

Fixing by a straight bar can never be
correctly ensured.

Hooked bars do not prevent vertical
layers from moving closer together, there-
fore, tying is necessary.

Bars bent into a U may be easily and
correctly tied to the main reinforcement and
is the best solution.

There are metal devices ensuring
simultaneously correct spaciftg of the
vertical bars (fixing by gripping) the cover
req.uired and the distance between the walls
of the shuttering. Plastic caps are fitted to
prevent corrosion of the metal piece on the
surface of the concrete {see Fig. 13.12).

•—ELASTIC CAP

Fig. 13.12 Spacers for Reinforcement and
Shuttering

c) In beams and columns — In beams, columns
and other elements the main bars» which are
parallel, are connected by tying to the
stirrups in order to form a rigid cage.

13.4.4 fixing Reinforcement in Relation to
the Shuttering — It is essential to maintain the
distance between the reinforcement and the
shuttering indicated on the drawing.

This is necessary to provide a uniform concrete
cover to the reinforcement so as to protect it from
corrosion.

13.4.4.1 Horizontal shuttering — In the case
of horizontal shuttering, the device used must be
able to support the following without risk of
piercing the shuttering:

— the weight of the reinforcement;

— supplementary loads resulting from the
placing of the concrets;

— supplementary loads due to movement of
workers over the reinforcement network.

In foundation pads, the layer of reinforcement
is placed on mortar or concrete blocks or on
strips of mortar cast in place between two joists.
These supports themselves rest either on blinding
concrete (general case) or directly on the ground
(see Fig. 13.13).

BOTTOM OF
SHUTTERING

MORTAR

COVER R COUmED

JOISTS (TO BE REMOVED BEFORE
CONCRETING)

Fig. 13.13 Strip of Mortar Cast on the
Shuttering (or on The Ground)

handbook on concrete reinforcement and detailing

201

SP : 34(S&T)-I987

The mortar should, of course, have hardened
sufficiently before the reinforcement is place.

The disadvantages attributed to this system
arise from the haste in placing reinforcement
structures which are often very heavy on mortar
which is too fresh and which is then likely to
break.

At the bottom of the shuttering, continuous
metallic supports are also used, the feet of which
are sometimes fitted with plastic caps to prevent
rust stains on visible surfaces, or continous
supports entirely in plastic. The latter model
presents the disadvantage of not guaranteeing
correct filling of the lower part by the concrete
(see Fig, 13.14).

METAtLfC
SUPPORTS

PLASTIC
SUPPORT

Fig. 13.14 Continuous Supports for Layers of
Reinforcement

The blocks or wedges of mortar are visible
after the shuttering has been removed if
their composition is differehr from that of
the concrete in the structure and if their-
porosity is likely to cause absorption of the
oil used for removal of the shuttering.

Bonding to the concrete is always well
assured, and no cracking is noted where the
block of mortar is located.

Rings of mortar through which the rein-
forcement is threaded are relatively fragile;
they can break when the reinforcement is
put in place in the shuttering.

Note — Mortar blocks as spacer blocks should not be
permitted on the faces in contact with the liquid in case
of reservoirs and tanks.

b) Asbestos-cement supports (Fig. 13.16) —
There are different forms, with or without
tying wire, which limit the area of contact
with the shuttering.

The mechanical strength is at least as
good as that of blocks of mortar; they are
less fragile and bond well with the concrete.

£3

For layers of reinforcement for reinforced
concrete road surfaces in the USA, bent ribbed
sheet-metal supports placed directly on the
ground are very widely used.

There is a very wide variety of individual
supports which may, for greater ease, be classified
according to the constitutent material:

a) Mortar supports (see Fig. 13.15) — The
. blocks of mortar are most often produced
on the site. The trend is, however, towards
an increasing use of prefabricated pieces, the
shape of which is sometimes more suitable
and the composition more homogeneous.
The blocks often have a tying wire in mild
annealed steel or in galvanised steel, or a
wire with two eyelets.

gThe area of contact with the shuttering
may be reduced by giving a hemispherical or
cylindrical shape to the block. In this case
adequate cover of the block is not always
ensured if the concrete used is very dry or
has undergone little vibration.

Fig. 13.15 Types of Mortar Block Support

Fig. 13.16 Types of Asbestos-Cement
Supports

:) Plastic supports — These are of two types;
(see Fig. 13.17).

a) Supports of the *chair' type on which the

bar is generally simply placed, some-
times gripped. They look like a cradle
resting on a cylindrical base or with
components which are either parallel or
crossed (cruciform contact with the
shuttering).

Supports of this type can generally
support heavy loads. They do on the
other hand have the disadvantage of
presenting a large area of contact with
the shuttering; some models have cavi-
ties, the complete filling of which with
concrete may create problem.

b) Supports of the 'circular* type which are

fixed to the reinforcement by gripping.
They are generally weaker and may give
way under the weight of heavy rein-
forcement.

They are certainly more suitable for
vertical reinforcement than for hori-
zontal reinforcement. The support must
be designed to allow good anchoring in
the concrete while not constituting too
large a discontinuity in the section
passing through its plane.

202

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

Fig. i 3. 1 7 Plastic Supports

Contact with the shuttering is limited
to the ends of the spokes or a very
limited portion of rim.

13.4.4.2 Vertical shuttering — Here the role
of the spacer is basically to maintain the desired
distance between the reinforcement and the wall
of the shuttering; the spacer does not have to bear
large loads.

It must, on the ofher hand, be correctly fixed to
the reinforcement /o that it does not move under
its own weight (vertical reinforcement), or at the
moment of concreting (fall of concrete, vibration,
etc).

This fixing is carried out either by binding
(mortar or asbestos cement blocks) or by the very
elasticity of the material (plastic spacers fixed by
gripping). The types listed in 13.4.4.1 may, in
general, be suitable on condition that they are
fixed correctly to the reinforcement.

In columns, in particular, it is better not to use
the circular type spacers on the vertical

reinforcement, since they constitute obstructions
when concreting; it is preferable to place them on
the horizontal reinforcement.

13.4.4.3 Upper reinforcement in slabs —
The upper network of reinforcement in slabs or
floors usually rests on the lower network by
means of chairs {see Fig. 13,18).

The reinforcement network sometimes rests on
the bottom of the shuttering by means of high
blocks of mortar or concrete (up to 15 to 20 cm
high) which are in the form of a pyramid or a
truncated cone.

High metal chairs, individual or continuous, are
also used and sometimes fitted with plastic caps.

13,4.5 Factors Determining the Choice of a
System — Table; 13.1 presents the factors
governing the choice of reinforcement supports.

When two figures are given for a single
characteristic, each concerns a support variant or

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

203

SP : 34(S&T)-1987

Fig. 13.18 High Metallic Chairs

a different method. It is necessary in this case to
refer to the corresponding comments.

It is obvious that some criteria may be essential,
for example, fire resistance, and that the use of

the table shall be altered accordingly.

It is advisable to avoid the use of supports,
specially mortar supports which are left behind on
the inner face of water retaining structures.

TABLE 13.1 THE CHOICE OF A SUPPORT

Factors to be Considered

Grade of A

Asbestos

Mor- Cem-
tar ent

PPRECl

ATION

Factors to be Considered

Grade of

appreciation

Plastic ^

Mor-
tar

Asbestos
Cem-
ent

Plastic '

'Chair

Cir- ^
cular

' Chair Cir- ^
cular

(1)

(2)

(3)

(4)

(5)

(1)

(2)

(3)

(4) (5)

Economic factors

Purchase price
Ease of storage and

handling
Speed and ease of

placing

3
1-3

2
2
1-3

2
1

Factors associated with
the device placed in the
concrete

Thermal treatment of
the concrete

3 3

Technical factors asso-
ciafed with the device
itself

Facing concrete (imme-
diately after removal
of shuttering)

2-3

4 3

Crushing strength
Strain under load
Uniformity of

dimensions
Use in cold weather
Scratching, scoring or

piercing of the

shuttering

1-2

2-3
1

1
\

1
2

3
3

2
3-4

Treatment of the
concrete surface

Bond with the concrete

Corrosion of the rein-
forcement

Fire resistance

2
1-2

2
2

2
i

4 3

3 3

4 4

1= excellent; 2 = good; 3 =

= admissible; 4= not recommended.

204

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SECTION 14
Typical Structural Drawings

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

SECTION 14
TYPICAL STRUCTURAL DRAWINGS

14.1 Some examples of structural drawings (see
pages 243-280) giving details of structural
elements— footings, columns, beams, slabs, etc,
are included. These are included for the purpose
of illustration only; they are not intended as
recommendations for design although they
generally meet the requirements of IS ; 456-1978.
These drawings are intended to emphasize how
design information is represented on structural
engineering drawings. Specific locations of cut off
points, bends, amounts of steel, etc, are shown as
examples to convey necessar^y information
through the drawings. These are not to be
considered as standard methods of detailing for a
specific structure.

The above drawings are based on the drawings

of different projects from different organisations*
and each one gives only a part of the information
relating to each structure/ project. These drawings
have been modified, wherever necessary, more or
less to suit the requirements of the Handbook.
Details of minor nature (as were relevant to the
situation) have also been deleted for the purpose
of this Handbook.

'BIS acknowledges with thanks the following organizations who
were helpful in providing the basic drawings on the basis of
which the present drawings have been included:

1. National Industrial Development Corporation
Limited, New Delhi;

2. Engineering Consultants (India), New Delhi;

3. Central Public Works Department (CDO), New Delhi;
and

4. Bharat Heavy Electricals Limited, New Delhi.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

207

As in the Original Standard, this Page is Intentionally Left Blank

APPENDIX

(Clause 4.4)
WELDING

SP : 34(S&T)-1987

A-0 GENERAL — Welded joints are permitted
in reinforcement (mild steel and deformed bars)
subject to the condition that in all cases of
important connections, tests shall be done to
prove that the joints are of the full strength of
bars connected.

A-1 WELDING OF MILD STEEL PLAIN
AND HOT ROLLED DEFORMED BARS

A-1.0 The requirements for welding mild steel
round and deformed bars conforming to mild
steel, Grade K conforming io IS : 432(Part 1)-
1982 'Specification for mild steel and medium
tensile steel bars and hard-drawn steel wire for
concrete reinforcement: Part T Mild steel and
medium tensile steel bars (third revision)" and hot
rolled deformed bars conforming to IS : 1786-
1985 'Specification for high strength deformed
steel bars and wires fot* concrete reinforcement
(third revision)* arc given in IS : 2751-1979 'Code
of practice for welding of mild steel plain and
deformed bars for reinforced concrete
construction (first revision)'.

Note I — Hot rolled deformed bars/ wires conforming to
IS : 1786-1985 will have thor transverse and longitudinal ribs
in straight lengths.

Note 2 — For guaranteed weldability, the percentage of
carbon shall be restricted to 0.25 percent, maximum.

A-LI Electrodes and Filler Rods

A-1. 1.1 Electordes — Covered electrodes for
manual metal arc welding shall conform to
IS : 814 (Part 1)-1974 'Specification for covered
electrodes for metal arc welding of structural
steel: Part I For welding products other than
sheets (fourth revision)" and IS : 814 (Part 2)-
1974 'Specification for covered electrodes for
metal arc welding of structural steel: Part 2 For
welding sheets (fourth revision)".

A-1.1.2 Fiiier Rods— Mild steel filler rods
for oxy-acetylene welding shall conform to type
S-FS7 of IS : 1278-1972 'Specification for filler
rods and wires for eas welding (second revision)'
provided they are tapable of giving a minimum
butt weld tensile Strength of 410 MPa.

A-1. 1.3 Mixtures for thermit welding shall be
capable of yielding weld metal of the required
composition and the tensile strength shall be at
least 410 MPa.

A-1.2 Flash Butt Welding ~~ Electric flash butt
welding may be adopted if a number of welds
have to be done at the same place and when the
electric supply is available of the required capacity
in respect of the cross-sectional area of the
maximum size of bar to be welded.

A- 1 .2. 1 Preparation for Welding -^ T he ends
of the bars to be welded shall be sheared off so
that fresh steel surfaces are available for welding.
The surfaces of the ends of the bars to be clamped
shall be cleaned free from rust to enable free flow
of electricity in the bars.

A-1.2.2 Procedure — The procedure for flash
butt welding shall generally be in accordance with
the indian Standard Recommended Procedure
for Flash Butt Welding' (under print).

A-l. 2.2.1 The ends of the bars to be welded
are placed in proper alignment in the clamps so
that bend or eccentric joints do not result. The
clamps should be cleaned before each welding
operation to avoid current losses and also to
eliminate harmful notches or grooves due to
burning in of spots of arcing.

A-1. 2.2.2 Welding should be done without
any preheating of bars. The bar ends shall be
uniformly pushed against each other from the
moment of contact up to the upsetting. The
transformer regulator should be so set that the
current at the contact area is between 85 and
90 A/mm2.

A-1. 2.2,3 If the butt welding machine or the
available power is not sufficient to take the load
for welding the bar in the cold condition, welding
may be done after preheating. By repeated
making and breaking of the contact arc, heat can
be made to spread over the entire cross-section of
the bar. The number of short circuits (contacts
and reversing) should be kept to the minimum
possible so that the welding time and spread of
heat in the longitudinal directions in the bar is
minimum. Satisfactory joints with only slight
reduction in the original strength of the bar
can be achieved with current densities up to
25A/mm2.

A-1.2.2.4 In automatic machines, the flash
rate should be so set that a continuous flash
without interruption can be achieved. If too high
a rate is set, then additional short circuits are
required leading to a heat spreading. If the rate is
too low, the flash will be interrupted,
consequently air penetrating into the joint will
form oxides. If the machine is hand operated, the
flash should be maintained to avoid interruption.

A-1 .2.2.5 Burn-off length — ¥ ox bars with
sheared ends a burn-off (flash-off) length of about
10 mm is required, this length being practically
independent of the bar diameter. Very short burn-
off length leads to defective welding because all
the impurities will not have been removed from
the place of welding. Increase in the burn -off

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

20**

SP : 34(S&T)-1987

length of the bar thus reducing the strength of the
bar,

A-1. 2.2.6 Upsetting — The upsetting should
result from the burning off, that is, without
interruption in the rain of sparks. The electric
supply should be switched off about 1/3 to I
second after the start of the upsetting or in the
case of automatic machine, after 1 to 3 minutes of
upset travel.

The voltage and frequency of the current
should be checked before commencing the
welding operation. Such deviations from the
nominal value or large fluctuations during the
operation may lead to gross defects in the
welding. Wherever possible, welding should be
done in periods of the day when the total load on
the network is fairly balanced.

A-^.3 Fusion Welding of Mild Steel Bars -

Steel bars shall be either butt welded or lap

welded using any of the following fusion welding
processes:

a) Manual metal-arc welding,

b) Oxy-acetylene welding,

c) Gas pressure welding, and

d) Thermit welding.

Thermit welding shall be generally in
accordance with the * Recommended practice for
fusion welding of ferrous metal by alumino-
thermic process* {under print),

A-1. 3.1 Butt Welding of Mild Steel Bars —
Bars may be spliced by butt welding them directly
or through a splice number such as angle, sleeve,
bars, etc.

A-1. 3.1.1 The preparation of edges for
different types of butt welds shall be in
accordance with Table A-1.

TABI i: A-1 EDGE PREPARATION FOR MANUAL METAL ARC WELDING

(Clause A- 1. 3.1.1)

No.

Dl-TAIL

Type of Joint

Symbolic
Representation

Size

Range

Application

(1)

(2)

TO 1-5 mm

(4)

BE3-

l5)

20 to
25mm

(6)

Where the root is
accessible for back-
chipping and apph-
:ation of a sealing
run.

-zS-

— JU-0 TO V

5mm

Smal-
ler bar
20 to
25mm
weld-
ed to
larger
bar

Where the root is
accessible for back-
chipping and appli-
cation of a sealing

r"^

■0 TO 3 mm

20 to
50mm

Where access to the
root of the weld is
unobtainable.
Alternatively a rem-
ovable copper back-
ing bar may be used
in place of the
integral steel backing
shown.

60-,^iL._0TO^-5mm

F^Rl

25 to
50mm

For general use;
Horizontal bars
should be turned
for flat position
welding^wherever
possible.

1— V5 TO A mm

e^3

40 to
50mm

Where access to
the root of the
weld is unobtainable.

{Continued)

210

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-19«7

TABLE A-1 EDGE PREPARATION FOR MANUAL METAL ARC WELDING (Contd.)

{Clause A-3.1.1.I)

A-1.3.1.2 The edges shall be prepared by
shearing, machining or oxy-acetylene flame
cutting. Bevelling may be done by chipping,
machining grinding/ or oxygen cutting. The joint
faces and the sur/ounding portion of the bars
shall be free from scale, dirt, grease, paint, rust
and contaminants.

A-1.3.1.3 When it is not possible to rotate
the bars for welding in flat position, the axis of the
bars shall be horizontal and the respective axes of
welds shall be vertical, that is, welds being carried
out in the vertical position.

A-1.3.I.4 In the case of inclined bars, the
edge preparation shall be such that welding is
done only on sides {see Fig. A-1).

A-1.3.1.5 All the bars to be welded should
be aligned and set up in position with their axes in
one straight line. The joints may not be out of
alignment by more than 25 percent of the
thickness of the thinner material for material up
to and including 12 mm thick, or by more than 3
mm for thicker material. Alignment may be
accomplished in a jig, or by means of a clamp or
by using guides. Rotation of the bars should be
avoided until they are adequately welded, so that
no disturbance to the alignment is caused and no
twist is introduced in the bars during the process
of welding.

A-1. 3.1. 6 In the case of deuils 4, 6, 7, 8 and
10 of Table A-1, back chipping in the root is

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

21 1

SP : 34(S&T)-1987

ANGLE OF
INCLINATION

Fig. A-1 Edge Preparation of Inclined Bars

recommended before welding is commenced on
second side. The root run and one further run
should be deposited on the first side. Where
possible the back chipping and root run on the
second side should thCn follow and the remaining
runs should preferably be deposited on alternate
sides of the joint to assist in controlling distortion.

A-1. 3.1.7 Indirect butt splices may be made
by welding bars to splice plate, angle, sleeve, etc,
using single or double fillet welds as shown in
Fig. A-2. The splice member used, that is, plate,
angle, bar, sleeve, etc, should have a cross-
sectional area such that its strength is at least 5
percent higher than the strength of the bars being
welded. The bars shall not be eccentric by more
than 3 percent of the bars joined. The angles when
used may be flattened to suit for welding higher
size bars.

A-1. 3.2 Lap Welding of Mild Steel Bars

A-1.3.2.1 Edge preparation is not necessary
for lap welds. The length of bars to be welded
should be free from scale, dirt, grease, paint, rust
and contaminants.

A-1. 3.2.2 The bars may be lap welded using
the details given in Fig. A-3. Detail given in Fig.
A-3(A) is used when the bars are in contact with
each others. If the bars are bent, the maximum
gap shall be 6 mm.

When the gap between bars is more than 6 mm
the joint should be made using a splice bar or
plate [see Fig. A-3 (A)]. The gap between the bar
and splice plate should not exceed 0.25 times the
diameter of the bar or 5 mm, whichever is less.
The area of the splice material shall be at least 5
percent more than the area of the higher size bar
being welded.

Some information regarding throat thickness
and reinforcement is given in Table A-2.

A-l .3.2.3 The dimensions of the fillet welds
(length and throat thickness) shall be capable of
developing the full strength of the bar. The

TABLE A-2 DETAILS FOR

LAP WELDED JOINTS

{ Clause

A-1

.3.2.2)

Bar DiAvuTfcR

Throat
Thickness

Min

Gap

HETWFFN
RKINFORCiiMLNT

(Afprox)

(1)

(2)

(3)

Up to

Over 12 up to

Over

12
16
16

1.5

3
3

Noll-; 1 If any overhead weid is required, it
should be made prior to the flat welds.

Note- 2 - If the bars are bent, the ma.ximum gap should
not exceed 6 mm.

eccentricity in the joint should be taken into
consideration in the design calculations.

A-1. 3. 3 Square Bull WVW5 — Square butt
welds may be used for direct butt welding and
shall be made using hydrogen controlled
electrodes or the thermit welding process.

A- 1. 4 Selection of Welded Joints

A-1.4.1 Direct butt splices (Table A-1) and,
as a second choice indirect butt splices {see Fig.
A-l), should be specified for bars of diameter 20
mm and over in order to reduce effects of
eccentricity.

A-l. 4.2 For bars of diameter up to 20 mm
indirect splicing {see Fig. A-l) may be used
although lap welds are normally adopted for such
bars.

A-l. 4.3 Square Butt Welds — l\\t bars may
be directly jointed with square butt welds provided
the welds are made using hydrogen controlled
electrodes or thermit welding process.

A-l. 5 Location of Welded Joints — Welded

joints should be staggered in the length of the

212

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

A-H

•20mm max.

SECTION AA A-H

A-2A INDIRECT BUTT SPLICE USING A PLATE

HE ANfGLE MAY BE
FLATTENED FOR
WELDING LARGE
DIAMETER BARS

A-2B INDIRECT BUTT SPLICE USING AN ANGLE

20 mm max

§ EXTERNAL FILLET WELD

SECTION BB

A-2C INDIRECT BUTT SPLICE USING A SLEEVE

SECTION CC

ii nM ii MHfUill

1^0

:=_ _^.

^T^i^r.-r-/

ENLARGED
SECTION 00

A-2D INDIRECT BUTT SPLICE USING TWO BARS

Fig. A-2 Indirect Butt Splices

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

213

SP : 34(S&T)-1987

A-3A LAP WELDING BARS IN CONTACT

((((((((({((((((({(({{((

U - f ff(ff(HU((K(f(((((( |

A-3B LAP WELDING BARS WITH BARS SEPARATED
BY A DISTANCE

Fig A-3 Lap Welding or Mild Stehl Bars

reinforced concrete components. The joints
should also not be positioned in highly stressed
areas.

A-1.6 Quality Control Tests

A-1.6.1 Butt Welds — Test pieces containing
butt welds ^t the centre in the *as welded'
condition shall be selected at the rale of one for
tensile test and one for nick break test for every
500 joints.

A-1.6.1. 1 Tensile test — The selected

pieces, when subjected to a tensile test, shall

have a tensile strength not less than 4l0 MPa
(42 kgf/mm2).

A-L6,1.2 Nick break test — The test specimen
shall be notched as given in Fig. A-4 and shall be
broken open along the weld, the fractured surface
visually examined for fusion, root penetration,
gas cavities and quality of weld metal. The surface
should be reasonably free from cavities,
inclusions, etc. There shall be no lack of fusion.
Small porosity may, however, be permitted.

A-1.6. 1.3 Bend test — The specimen shall
be bent using any suitable jig. The weld joint
should be capable of being bent to an angle of 60°
around a mandrel of diameter equal to diameter
of bar before any crack appears.

A-1.6*2 Lap Joints — Test pieces containing
lap joints at their centre shall be selected at the
rate of I per 500 joints.

A-1 .6.2.1 Tensile test — The load required
to shear the joint shall be at least equal to the
tensile load required to fracture the bar.

Note- When pulling lap weld specimens to determine
the tensile strength a jig should be used to prevent
distortion due to secondary stresses. The jig may be of
design and detail preferred by the testing agency but
should prevent change in geometry of the specimen as it is
being pulled.

A-1.7 Retests — If a sample selected for testing
fails to meet the requirements given under
A-1.6.1 or A-1.6.2, the purchaser or his
representative shall select two further samples
from the same lot. If on testing, either of the
samples fails to meet the specified requirements,
the whole lot shall be rejected.

A-1.8 Inspection — For purpose of inspection
reference shall be made to IS : 822-1970 *Code of
procedure for inspection of welds'.

A-1.8.1 The weld size, length and location
shall be as stipulated in the drawings, and the
metal designated shall De free from cracks,
excessive slag inclusions and excessive porosity.

A-1.8.2 The weld metal shall be properly
fused with the parent metal without overlapping
at the toes of the weld.

A-1.8.3 There shall be no cracks in the heat
affected zones of the reinforcing bars or splice
members

A-1.8.4 There shall be no serious undercuts in
joint subjected to tension.

A-1,8.5 All craters shall be filled to the cross-
section of the welds.

A-1.8.6 The visible surfaces of all welds shall
be free from entrapped slag and shall be regular*
and of consistently uniform contour.

214

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T).1987

Fig. A-4 Nick Break Test Specimens

A-1.8.7 All direct butt welds shall be of full
cross-section with maximum reinforcement of
3 mm and shall blend smoothly into the face of
bars.

A-l.ft.8 The profile of fillet welds shall be
substantially flat or slightly convex.

A-2 WELDING OF COLD-WORKED
STEEL BARS

A-2.0 The recommendation for welding cold-
worked steel bars^ conforming to IS : 1786-1985 is
given in IS : 9417-1979.

Note 1 — Cold-work deformed bars conforming to
IS : 1786- 1 985 will have 'their longitudinal and transverse
ribs twisted and not in straight lines.

Note 2 — For guaranteed weldability, the percentage of
carbon shall be restncted to 0.25 percent, maximum.

A-2.1 . Electrodes — Electrodes used shall
conform to IS : 814{Part 1)-1974 and
IS:814(Part 2)- 1974 .

A-2.2 Procedure — Cold-worked steel bars shall
be either butt- welded or lap-welded. Butt-welding
may be carried out either by resistance butt or
flash butt or by manual metal arc welding
process.

A.2.2.1 Resistance Butt Welding and Flash
Butt Welding of Cold-Worked Ai/-5 — Flash or
resistance butt welding may be adopted if a large
number of welding has to be done at the same
place ana when the electric supply is available of
the required capacity in respect of the cross-
sectional area of the maximum size of bar to be
welded.

A-2.2.1.1 Preparation for welding ^Jh^
ends of the bars and the extreme untwisted ends
of new bar shiill be sheared off so that fresh steel
surfaces are available for welding, the surfaces of
the ends of the bars to be clamped shall be
cleaned free from' rust to unable free flow of
current in the bars.

A-2.2.L2 Procedure — The ends of the bars
to be welded are placed in proper alignment in the
clamps so that bent or eccent^c joints do not
result. The clamps should be cleaned before each
welding operation to avoid current loss and to
eliminate harmful notches or grooves due to
burning in of spots of arcing.

The bar ends shall be uniformly pushed against
each other from the moment of contact up to the
upsetting. The transformer regulator should be

so set that the current at the contact area is
between 85 and 90 A/mm^.

If the capacity of butt welding machine or the
available power is not sufficient to take the load
for welding from cold, welding may be done after
preheating. By making and breaking of the contact
arc repeatedly, heat can be made to spread over
the entire cross-sections of the b^rs. The number
of -short-circuits (contacts and reversing) should
be kept to the minimum possible so that the
welding time and spread of heat in the
longitudinal direction in the bar is minimum.
Satisfactory joints with only slight reduction in
the original strength of the bar can be achieved
with a current densities up to 25 A/mm^.

In automatic machines the flash rate should be
so set that a continuous flash without interruption
can be achieved. If too high a rate is set, then
additional short-circuits are required leading to a
heat spreading. If the rate is too low, the Hash will
be interrupted, consequently air penetrating into
the joint will form oxides. If the machine is hand-
operated, the flash should be maintained to avoid
interruption. Too long flashes lead to generation
of large quantities of heat thus removing the effect
of cold- working in the bar.

Burn-off length — For bars with sheared ends, a
burn-off (flash-ofO length of about 5 to 7 mm is
required, this length being practically independent
of the bar diameter. Very short burn-off lengths
lead to defective welding because all the
impurities will not have been removed from the
place of welding, hicrease in the burn-off length
will spread heat along the length of the bar thus
reducing the strength of the bar.

Upsetting — T\\c upsetting should result from
the burning off, that is, without interruption in
the rain of sparks. The electric supply should be
switched off about 1/3 to 1 second after the start
of the upsetting or in the case of automatic
machine after I to 3 mm of upset travel.

The voltage and frequency of the current
should be checked before commencing the
welding operation. .Such deviations from the
nominal value or large fluctuations during the
welding. Wherever possible, welding should be
welding. Wherever possible welding should be
done in periods of the day when the total load on
the network is fairly balanced.

A-2.2.2 Butt-Welding by Metal-Arc Welding
Process — Butt- welds are normally adopted to

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

215

SP : 34(S&T)-1987

join bars of thickness more than 20 mm. Welding
electrodes with flux covering of Type 3 or 6 {see
IS : 815-I974*Classification and coding of
covered electrodes for metal arc v elding^ of
structural steel {second revision) ' are
recommended for better results depending on the
size of bar to be welded.

A-2.2.2.1 Preparation for welding

The preparation of the edges of the rods shall
be as shown in Fig. A-5. The edges shall be
prepared by shearing, machining or oxy-acetylene
flame cutting. Bevelling may be made by
machining, grinding or oxy-acetylene cutting. The
fusion faces and the surrounding material shall be
free from scale, dirt, grease, paint, rust and
contaminants.

When it is not possible to rotate the bars for
welding in flat position, the axis of the bars shall
be horizontal antl the respective welding shall be
vertical, that is, the welds being carried out m the
vertical position.

In the case of non-rotatable inclined bars, the
edge preparation shall be such that welding is
done only on sides {see Fig. A-5).

AH the bars to be butt welded should be aligned
and set up in position with their axis in one
straight line. This may be done in a jig or by
means of a clamp or by using guides. Rotation of
the bars should be avoided until they are
adequately welded, so that no disturbance to the
alignment is caused and no twist is introduced in
the bars during the process of welding. The joints

may not be out of alignment by more than 25
percent of the thickness of the thinner material up
to and including 12 mm thick, or by more than

3 mm or thicker material,

A-2. 2.2.2 Electrodes — The electrodes shall
be so selected that relatively short beads can be
rapidly made, since with each bead only a small
quantity of heat is transferred to the steel which
the steel can conduct away without any harmful
effects on the material. If the electrodes move out
slowly, a concentration of heat takes place thus
removing the effects of cold-working on the bar.

The size of electrode depends upon the length
of the bead and thickness of the bar to be welded.
The root runs should be made with electrodes of
size 3.15 mm. With the number of beads the size
of electrode should be gradually increased from
3. 1 5 to a maximum size of 5 mm for the top bead.

A-2. 2. 2. 3 Welding procedure and
technique — The sequence of welding beads is
shown in Fig. A-6 for information. The runs ! to

4 are made in the position of welding best suited
for the quality of the weld. Besides the
interruption in welding required for cleaning of
each bead, a pause shall be made after every
second bead and the bar is allowed to cool down.
The temperature of the bars at a distance of about
20 mm from the joint shall not exceed 300*^0
immediately after the bead is made. Before
commencing the next bead, the temperature shall
not exceed 250''C. The temperatures can be
checked approximately using temperature
indicating crayons.

ANGLE OF
INCLINATION

Fig. A-5 Edge Preparation of Inclined Bars

SEQUENCE OF 4 9 3 2 1
FUSION FACES TO WELDING:
BE'CLEAN

216

SEQUENCE OF
2 TO 3mm WELDING: ^ ^

Fig. A-6 Sequence of Welding Beads

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

Alter completing the bead 4, *he bars are
rotated by 180'* about their axes, and the beads 5
to 8 are made in a manner described above. The
final bead 9 is made in the case of horizontal and
freely rotatable bars by weaving in the direction
of the bar periphery, the bars being continuously
rotated during welding.

In the case of vertical, inclined and non-
rotatabie bars the beads 1 to 4 shall be made as
explained in this clause. The top bead is made by
making separate annular runs (see Fig. A-7), the
electrode being drawn up to the edge of the top
bead. The starting and withdrawal position of the
electrodes are shown in Fig. A-7. The top beads
are made by drawing the adjacent beads in the
longitudinal direction of the bar. The diameter
measured over the top of the butt welded joint
shall be equal to at least 1.2 times the diameter of
the bar.

A-2,2.3 Imp Welding of Cold- Worked Bars —
Lap joints may be made in bars of all sizes and
qualities of cold-worked bars. They are preferred
when access for welding is from only one side and
while connecting prefabricated units. Use of
electrodes with flux covering of type 3 or 6 are
recommended for better results depending on the
size of bar being welded.

A-2.2.3.1 Edge preparation is not necessary
for lap welds. The joint faces and the surrounding
material shall be free from scale, dirt, grease,
paint, rust and contaminants.

A-2.2.3.2 Electrodes — The size of
electrodes according to the diameter of the bar to
be welded shall be as follows:

Size of Bar

Up to and including 6
Over 6 up to and including 10
Over 10 up to and including 14
Over 14 up to and including 20
Over 20

tLECTHOOe
APfiXATtON

Size of

Electrode,

Min

1.6
2.0

2.5

3.15

A-2.2.3.3 Procedure — Tht arc should be
struck as shown in Fig. A-8 somewhere in the
middle of the joint and not at its beginning.

The movement of the electrode for welding lap
joints in the horizontal and vertical position is
indicated in Fig. A-8.

In Fig. A-9 to A- 12 are given the various lap
joints used to connect cold -worked bars.

A-2.3 Quality Control Tests

A-2.3.1 Butt Welds — J^si pieces containing
butt welds at the centre in the as welding
condition shall be selected at the rate of one for
tensile test and one for bend test for every 500
joints.

A-2.3. 1.1 Tensile test — The selected pieces,
when subjected to a tensile test, shall have a
tensile strength not less than 90 percent of the
actual tensile strength of the bar but in no case
less than the tensile strength of the bar specified in
IS : 1786-1985. The fracture shall take place away
from the weld.

A-2.3.1.2 Bend test — The welded joint
should be capable of being bent to an angle of 60°
around a mandrel of diameter equal to diameter
of bar before any crack appears.

A-2J.2 Lap Joints — The pieces containing
lap joints at their centre shall be selected at the
rate of one in 500 joints.

A-2.3.2.1 Tensile test — Tht load required
to shear the lap joint shall be at least equal to the
tensile load required to fracture the bar.

A-2.4 Retests — If a sample selected for testing
fails to meet the requirements given under A-2.3.1
and A-2.3.2, the purchaser or his representative
shall take two further samples from the same lot.
If on testing either of the samples fails to meet the
specified requirements, the whole lot shall be
rejected.

ELECT RODE
WIIHORAWL

ANNUtAR
RUN

Fig. A-7 Making of Top Bead

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

217

SP : 34(S&T)-1987

HORIZONTAL
WELDING _

STRIKING OF ARC^ WITHDRAWL

WITH OR AWL

VERTICAL
WELDING

STRIKING OF ARC

A-8A WEI.DING IN THE HORIZONTAL POSITION A 8B WELDING IN THE VERTICAL POSITION

Fig. A-8 Wlldinc; of Lap Joints

»0-3<t-J

1 Strike the arc with the electrode; the arc striking point should lie in the gap
which is finally welded.

2 Welding dislocation.

3 Electrode withdrawal.

4 Bar to be spliced.

Fig. A-9 Lap Joint Using Stages

GAP 2 TO 3mm — j h^««0*2d

Fig. A-IO Lap Joint

218

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

Fig. A-1 1 Lap Joint

Fig, A-12 Lap Joint

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIIJNC.

219

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34<S&T)-1987

APPENDIX B

{Clause 5.9.1)

ISO 4066-1977 BUILDING AND CIVIL ENGINEERING DRAWINGS-BAR SCHEDULING*

B-0. INTRODUCTION

The purpose of this International Standard is to
ensure uniformity of practice in the scheduling of
steel bars for the reinforcement of concrete. To
establish a clear and unambiguous system for
scheduling, it is necessary to specify the method of
indicating dimensions to be used and the order in
which the information is given on the bar
schedule.

As the use of preferred shapes is considered to
be very advantageous both for simplifying design
and manufacture and for the use of coniputers,
the opportunity has been taken to include a list of
preferred shapes and a coding system; the layout
of the bar schedule is based on the use of
preferred shapes.

B-1. SCOPE

This International Standard establishes a system
for the scheduling of reinforcing bars, and
comprises

— the method of indicating dimensions;

— a coding system for bar shapes;

— a list of preferred shapes;

— the bar schedule.

B-2. FIELD OF APPLICATION

This International Standard applies to all types of
steel bar for the reinforcement of concrete.

Steel fabric and prestressing steel reinforcement
are excluded.

B-3. METHODS OF INDICATING
BENDING DIMENSIONS

The bending dimensions shall be indicated as
shown in Fig. B-l t* B-5.

Dimensions shall be outside dimensions except
for radii and the standard radius of bend shall be
the smallest radius permitted by national
standards or regulations.

The total length (cutting length) shall be
calculated on the basis of the appropriate bending
dimensions with corrections for bends and
allowances for anchorages.

*This ISO standard is reproduced here in full as a supplement
to the information contained in this handbook.

B-4. CODING SYSTEM FOR BAR SHAPES

The shape code number consists of two or» if
essential, three or four characters, as defined in
Table B-1.

B-5. LIST OF PREFERRED SHAPES

When a third character is used, the direction of
the end anchorages shall be as shown by the
dotted lines in the examples in Table B-2.

It is recognized that in some countries hooks
are used for end anchorages.

The letter symbols refer to the dimensions
which shall be given in the bar schedule.

B-6. BAR SCHEDULE

The bar schedule is the document used to
specify and identify reinforcing bars. The format
specified below incorporates the use of preferred
shapes,

B-6. 1 Information content

A bar schedule shall contain the following
information in the sequence listed below:

a) member — identification of the structural
member in which the bar is located;

b) bar mark — unique reference of the bar;

c) type of steel;

d) diameter of bar;

e) length of each bar (cutting length, allowing
for loss or gain at bends, calculated from the
dimensions and radii given in (k); see B-3);

f) number of members;

g) number of bars in each member;
h) total number of bars [(f) X (g)];
j) total length [(e) X (h)];

k) shape code (as defined in B-5);
m) bending dimensions;
n) revision letter;
p) title block.

An example of a form of bar schedule is shown

on page 236.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

221

SP : 34<S&T)-I987

BENDING DIMENSIONS

Fig. B-1

Fig. B-2

if-

^ ^ f

r^\

\ I

Fig. B-3

Fig. B-4

c \ PMHvkM/t of oomptott tiwnc

Fig. B-5

222

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP:34(S&T)^!987

B-6.2 Special shapes

When special shapes are required, these shall be
shown by a dimensioned sketch drawn in the
space normally used for bending dimensions.

B-63 Title Block

The title block shall be placed below the schedule,
and shall contain the following information:

a) name of the structural designer;

b) title of the project;

c) date prepared
prepared by ...
checked by ...

d) drawing number;

e) bar schedule reference;

revision letter and date of last revision;
and

g) a statement that the schedule has been pre-
pared in accordance with the requirements
of ISO 4066.

B-7. SUMMARY SHEET

If required, summary sheets may be used; separate
sheets shall be used for each type of steel.

TABLE B-l CODE NUMBER COMPOSITION

First Characthr

0— No bends (optional)

1 — 1 bend

2 — 2 bends

3 — 3 bends

4 — 4 bends

5 — 5 bends

6 " Arcs of circles

7 — Helices

Second Chara<tkr

0-- Straight bars (optional)

1 ~ W bend(s) of standard

radius all bent in the
same direction

2 — 90° bend(s) of non-

standard radius, alt bent
in the same direction

3 - ISO" bend(s) of non-

standard radius, all bent
in the same direction

4-90° bends of standard
radius not all bent in the
same direction

5 ~ Bends < 90°, all bent in
the same direction

6- -Bends <90°, not all bent
in the same direction

7 — Arcs or helices

81 to 89 — Shapes defined in national standards

99 -_ Special non-standard shapes defined by a sketch

It is recommended that code shapes 99 for all
non-standard shapes be used. However, the
numbers 91 to 99 are available for countries which
require more than one number for special shapes

THIKH CllARAtTl-R

No end anchorage

(optional)

End anchorage at one end,

as defined in national

standards

End anchorages at both
ends, as defined in
national standards

Fourth Cuaractkr

- Where a national standard)
specifies a special radius
of bend (for example
stirrups, links) this shall
be indicated by use of
the charactrcr .V,

Note — The table explains the logic behind the numbering of the shapes in Table B-2. It is not to be used for making
up codes for additional shapes.

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

223

SP : 34(S&T)-I987

TABLE 8-2 PREFERRED SHAPE

Shape

CODE

Shapes

Examples

j:::^

U ^^

^Jv

J--^-^

{Continued)

llA

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

SP : 34(S&T)-1987

TABLE B-2 PREFERRED SHAPES * Continued

Shape

CODE

Shapes

Examples

J rt

)f-

m '1

«i

□ I

C_D

J-^«-^

y-i-

^-^-^

.y^

U ^

>-^

tJ 'O

//^

c : numbir of complMB turns

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAIUNG

225

EXAMPLE OF ISO BAR SCHEDULE

All dimensions in millimetres.

o
p
^

o
■z

n
o
z

n
yo
m

H
X

S
z

m
z

o
o

H
>

[VieiiiDer

Bar mark

Type of
steel

Length of
each bar

Number

of
members

dumber
of bars
in each
member

total
number

Total

Shape

Bending dimensions

' 1

Revision
letter

Uiantcv

length

code

ejr

1 —

1 ,

_■_

A. B.CEOtndPAPITNERS
2 XY StrMt. London WIA

(TITLE OF PROJECT!

Preparation d«t«

Orcwing nomb«f

Rtvition date

Prapartd by

Revision letter

ChKlttdbv

This ichadula hat baen prapared in

with the raquiramanu of ISO 4066.

SP : 34(S&T)-1987

APPENDIX C

DIMENSIONS AND PROPERTIES OF HARD DRAWN STEEL WIRE FABRIC AND

OTHER BARS

TABLE C-1 DIMENSIONS AND

PROPERTIES OF HARD-DRAWN STEEL WIRE FABRIC

(SQUARE AND OBLONG MESH)

Mesh Size

DUMETER

Nominal

Mesh

Size

Diameter

Nominal

No.

(Nominal Pitch

OF Wire

Weight

No.

(Nominal Pitch

Wire

Weight

OF Wires)

Each Way

OF Wires)

Each wav

(i)

(2)

(3)

(4)

(1)

(2)

(3)

(4)

kg/m^

kg/m*

Mesh

A. Sqarc

ream

cross

main

cross

3.0

2.220

300

5.3

3.6

2.580

3.8

3.560

300

5.6

3.55

2.83

3.0

6.160

300

5.8

3.6

3.040

100

3.4

1.430

300

6.0

5.0

3.470

100

3.6

1.600

300

6.5

4.0

3.80

100

4.0

1.980

300

6.5

6.0

4.260

too

4.5

2.530

300

7.0

4.0

4.360

100

4.8

2.840

300

8.0

4.8

5.730

too

5.0

3.080

300

9.0

4.8

7.130

100

5.3

3.460

300

10.0

5.8

8.910

100

5.8

4.140

400

9.0

4.75

7.00

100

6.5

5.200

400

9.5

5.6

7.90

100

7.0

6.040

400

10.0

5.6

8.71

iOO

8.0

7.900

400

8.0

4.75

5,60

150

3.15

0.82

400

7.5

4.75

4.97

150

3.6

1.060

400

7.1

4.5

4.46

150

4.0

1.320

400

6-3

4.0

3.50

150

4.5

1.660

100

150

4.2

3.0

1.460

150

4.75

1.85

100

150

4.5

1.620

150

5.0

2.060

100

150

4.6

3.0

1.670

150

5.3

2.300

100

150

4.8

3.6

1.950

150

5.6

2.57

100

150

5.0

3.0

1.910

150

5.8

2.760

100

150

5.3

3.6

2.260

150

6.0

2.360

100

150

5.5

3.0

2.240

150

6.3

3.27

100

150

5.8

3.6

2.600

150

6.5

3.480

100

150

6.5

4.0

3.260

150

7.1

4.14

100

150

7.0

4.0

3,680

150

7.5

4.62

100

250

4.2

1.530

150

8.0

5.260

100

250

5.0

4.2

1.960

150

9.0

6.660

100

250

5.5

4.2

2.300

150

10.0

8.220

too

250

7.0

5.0

3.640

200

4.0

0.980

100

300

4.0

3.0

1.180

200

4.5

1.260

100

300

4.2

5.0

1.640

200

4.8

1.420

100

300

4.5

3.0

1.440

200

5.3

1.740

100

300

4.2

1.450

200

5.8

2.080

100

300

4.8

3.6

1.680

200

6.5

2.600

100

300

5.0

2.100

200

7.0

3.020

100

300

4.0

4.20

1.900

200

8.0

3.940

100

300

5.0

3.0

1.730

200

9.0

5.300

100

300

5.3

3.6

2.000

200

10.0

6.160

100

300

5.8

3.6

2.340

100

300

6.0

5.0

2.730

B. Oblong Mesh

-_JL._^

100

300

6.5

4.0

2.930

„ , X .1

98
99

100
(00

300
300

7.0
7.0

4.0
5.0

3 350

'^main Jross^

*main cross^

3.530

75 '250

5.0

4.2

2.490

too

100

300

7.0

5.5

3.640

75 250

4.2

1.09

101

100

300

7.5

6.0

4.210

75 250

6.0

5.0

3.580

102

too

300

8.0

4.8

4.420

75 300

3.15

2.65

0,96

103

100

300

8.0

6.0

4.690

75 300

3.55

2.65

1.18

104

100

300

8.0

6.5

4.820

75 300

4.0

2.65

1.45

105

too

300

9.0

4.8

5.460

75 300

4.0

3.0

1.510

106

100

300

10.0

5.8

6.860

75 300

4.5

3.15

1.870

107

150

250

5.0

4.2

1.440

75 300

4.7

3.15

2.06

108

130

250

6.0

5.0

3.300

75 300

4.8

3,6

2.160

109

ISO

250

6.5

5.5

3.900

75 300

5.0

4.2

2.420

ISO

300

6.0

5.0

2.070

75 300

5.0

2.600

ISO

300

7.0

5.0

2.520

75 300

5.3

3.15

2.51

112

ISO

300

8.0

6.0

3.490

HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

227

SP:34(SftT)-1987

TABLE €-2 REINFORCEMENT CHARACTERISTICS- AREA« WEIGHT AND PERIMETER

Size

Area

Weight Peri-

Length

Size

Area

Weight Peri-

Length

meter

Per Toni^

meter per Tonne

(2)

(3) (4)

(5)

(1)

(2)

(3) (4)

(5)

(cm2)

<kg/m) (cm)

(m)

(cm^)

(kg/m) (cm)

(m)

0.283

0.222 l.«9

4310

3.801

2.980 6.91

336

0.503

0.395 2.51

2332

4.909

3.854 7.85

260

0.785

0.617 3.14

1621

6.157

4.830 8.80

207

1.131

0.888 5.77

1125

8.042

6.313 10.05

159

1.539

1.206 4.40

829

10.179

7.990 11.31

125

2.011

1.578 5.03

633

12.566

9.864 12.57

lot

2.545

2.000 5.65

500

15.904

12.490 14.14

3.142

2.466 6.28

405

19.635

15.410 15.71

22S HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

Number
OF Bars

TABLE C-3 AREAS OF GROUPS OF STANDARDS BARS (IN SQUARE CENTIMETRES)

Bar Diameter in mm

0.28

0.50

0.79

1.13

1.54

2.01

2.54

3.14

3.80

4.91

6.16

8.04

10.18

0.56

1.00

1.57

2.26

3.07

4.02

5.08

6.28

7.60

9.81

12.31

16.08

20.35

0.84

1.50

2-35

3.39

4.61

6.03

7.63

9.42

11.40

14.72

18.47

24.12

30.53

1.13

2.01

3-14

4.52

6.15

8.04

10.17

12.56

15.20

19.63

24.63

32.17

40.71

1.41

2.51

3.92

5.65

7.69

10.05

12.72

15.70

19.00

24.54

30. /8

40.21

50-89

1.69

3.01

4.71

6.78

9.23

12.06

15.26

18.85

22.80

29.45

36.94

48.25

61.07

1.97

3.51

5.49

7.91

10.77

14.07

17.81

21.99

26.60

34.36

43.10

56.29

71.25

2.26

4.02

6.28

9.04

12.31

16.08

20.35

25.13

30.41

39.27

49.26

64.34

81.43

2.54

4.52

7.06

10.17

13.85

!8.09

22.90

28.27

34.21

44.17

55.41

72.33

91.60

2.82

5.02

7.85

11.31

15.39

20.10

25.44

31.41

38.01

49.08

61.57

80.42

101.78

3.11

5.52

8.63

12.44

16.93

22.11

27.99

34-55

41.81

53.99

67.75

88.46

f 11.96

3.39

6.03

9.42

13.57

18.47

24.12

30.53

37.69

45.61

58.90

73.89

96.51

122.14

3.67

6.53

10.21

14.70

20.01

26.13

33.08

40.84

49.41

63.81

80.04

104.55

132.32

3.95

7.03

10.99

15.83

21.55

28.14

35.62

43.98

53.21

68.72

86.20

112.59

142.50

4.24

7.54

n.78

16.96

23.09

30.15

38.17

47.12

57.02

73.63

92.36

120.63

152.68

4.52

8.04

12.56

18.09

24.63

32.17

40.71

50.26

60.82

78.54

98.52

128.68

162.86

4.80

8.54

13.35

19.22

26.17

34.18

43.26

53.40

64.62

83.44

104.67

136.72

173.03

5.08

9.04

14.13

20.35

27.70

36.19

45.80

56.54

68.42

88.35

110.83

144.76

183.21

5.37

9:55

14.92

21.48

29.24

38.20

48.34

59.69

72.22

93.26

116.99

152.80

193.39

5.65

10.05

15.70

22.62

30.78

40.21

50.89

62.83

76.02

98.17

123.15

160.85

203.57

o
o

ri
;o
w

H
W

90
w
z

"J5
O

;o
o
m

H
>;

r
z

TABLE C-4 PERIMETER OF GROUPS OF STANDARD BARS

(IN CENTIMETERS)

Number
OF Bar ,

Bar Diametfr

rN mm

2
3
4

1.88
3.77
5.65

7.54

2.51

5.02

7.54

10.05

3.14

6.28

9.42

12.56

3.77

7.54

11.31

15.08

4.40

8.79

13.19

17.59

5.03
10.05
15.08
20.10

5.65
11.31
16.96
22.62

6.28
12.56
18.85
25.13

6.91
13.82
20.73
27.64

7.85
15.70
23.56
31.41

8.80
17.59
26.38
35.18

10.05
20,10
30.15
40,21

11.31
22.62
33.92

45.23

5
6
7
8

9.42
11.31
13.19
15.08

12.56
15.08
17.59
20.10

15.70
18.85
21.99
25.13

18.85
22.62
26.38
30.15

21.99
26.38
30.78
35.18

25.13
30.15
35.18
40.2!

28.27
33.92
39.58

45.23

31.41
37.69
43.98
50.26

34.55
41.46

48.38
55.29

39.27
47.12
54.97
62.83

43.98

52.77
61.57
70.37

50.26
60.31

70.37
80.42

56.54
67.85
79.16
90.47

9
10
II
U

16.96
18.85
20.73
22.62

22.62
25.13
27.64
30.15

28.27
31.41
34.55
37.69

33.92
37.69
41.46
45.23

. 39.58
43.98
48.38

52.77

45.23
50.26
55.29
60.31

50.89
56.54
62.20
67.85

56.54
62.83
69.11
75.39

62.20
69.11
76.02
82.93

70.68
78.54
86.39
94.24

79.16

87.96

96.75

105.55

90.47
100.53
1 10.59
120.63

101.78
113.09
124.40
135.71

13
14

rs
r6

24.50
26.38
28.27
30.15

32.67
35.18
37.69
40.21

40,84
43.98
47.12
50.26

49.00
52.77
56.54
60.31

57.17
61.57
65.97
70.37

65.34
70.37
75.39
80.42

73.51
79.16
84.82
90.47

81.68
87.96
94.24
100.53

89.85

96.76

103.67

110.58

102.10
109.95
117.81
125.66

1 14.35
123.15
131.94
140.74

130.69
140.74
150.79
160.85

147.02
158.33
169.64
180.95

17
18
19
20

32.04
33.92
35.81
37.69

42.72
45.23
47.75
50.26

53.40
56.54
59.69
62.83

64.08
67.95
71.62
75.39

74.77
79.16
83.56
87.96

85.45
90.47
95.50
100.53

96.13
101.78
107.44
113.09

106.81
113.09
119.38
123.66

117.49
124.40
131.31
138.23

133.51
141.37
149.22
157.08

149.54
158.33
167.13
175.93

170.90
180.95
191.00
201.06

192.26
203.57
214.88
226.19

TABLE C-5 AREAjOF BARS IN SLABS (IN SQUARE CENTIMETRES PER METRE WIDTH)

Spacing
cm

Bar Diameter in inm

5.65

10.05

15.71

22.62

30.79

40.21

50.89

62.83

76.03

98.17

123.15

160.85

4.71

8.38

13.09

18.85

25.66

33.51

42.41

52.36

63.36

81.81

102.68

134.04

4.04

7.18

11.22

16.16

21.99

28.72

36.35

44.88

54.30

70.12

87.96

114.89

3.53

6.28

9.82

14.14

19.24

25.13

31.81

39.27

47.52

61.36

76.97

100.53

3.14

5.58

8.73

12.57

17.10

22.34

28.27

34.91

42.24

54.54

68.42

89.36

2.83

5.03

7.85

11.31

15.39

20.11

25.45

31.42

38.01

49.09

61.57

80.42

2.57

4.57

7.14

10.28

13.99

18.28

23.13

28.56

34.56

44.62

55.98

73.11

2.36

4.19

6.54

9.42

12.83

16.75

21.21

26.18

31.68

40.91

51.31

67.02

2.17

3.87

6.04

8.70

11.84

15.47

19.57

24.17

29.24

37.76

47.37

61.86

2.02

3.59

5.6!

8.08

11.00

14.36

18.18

22.44

27.15

35.06

43.98

57.45

1.88

3.35

5.24

7.54

10.26

13.40

16.96

20.94

25.34

32.72

41.05

53.62

1.77

3.14

4.91

7.07

9.62

12.57

15.90

19.63

23.76

30.68

38.48

50.27

1.66

2.96

4.62

6.65

9.05

11.83

14.97

18.48

22.36

28.87

36.22

47.31

1.57

2.79

4.36

6.28

8.55

11.17

14.44

17.45

21.12

27.27

34.21

44.68

1.49

2.65

4.13

5.95

8.10

10.58

13.39

16.53

20.01

25.84

32.41

42.33

1.41

2.51

3.93

5.65

7.70

10.05

12.72

15.71

19.01

24.54

30.79

40.21

1.35

2.39

3.74

5.39

7.33

9.57

12.12

14.96

18.10

23.37

29.32

38.30

1.28

2.28

3.57

5.14

7.00

9.14

11.57

14.28

17.28

22.31

27.99

36.56

1.23

2.18

3.41

4.92

6.69

8.74

11.06

13.66

16.53

21.34

26.77

34.97

1.1«

2.09

3.27

4.71

6.41

8.38

10.60

13.09

15.84

20.54

25.66

33.51

1.13

2.01

3.14

4.52

6.15

8.04

10.18

12.57

15.20

19.63

24.63

32.17

1.09

1.93

3.02

4.35

5.92

7.73

9.79

12.08

14.62

18.88

23.68

30.93

1.05

1.86

2.91

4.19

5.70

7.45

'9.42

11.64

14.08

18.18

22.81

29.79

I.OI

1.79

2.80

4.04

5.50

7.18

9.09

11.22

13.58

17.53

2L99

28.76

0.97

1.73

2.71

3.90

5.31

6.93

8.77

10.83

13.11

16.93

21.23

27.73

0.94

1.68

2.62

3.77

5.13

6.70

8.48

10.47

12.67

16.36

20.52

26.81

0.88

1.57

2.45

3.53

4.81

6.28

7.95

9.82

11.88

m:44

19.24

25.13

0.83

1.48

2.31

3.33

4.53

5.91

7.48

9.24

11.18

18.11

23.65

0.78

1.40

2.18

3.14

4.28

5.58

7.07

8.73

10.56

13.63

17.10

22.34

0.74

1.32

2.07

2.98

4.05

5.29

6.70

8.27

10.00

12.92

16.20

21.15

o.7r

1.26

1.96

2.83

3.85

5.03

6.36

7.85

9.50

12.27

15.39

20.11

C/3

SP : 34(S&T)-1987

BIBLIOGRAPHY

1. IS : 456-1978 Code of practice for plain and reinforced concrete {third revision).
Indian Standards Institution

2. IS : 2502-1963 Code of practice for bending and fixing of bars for concrete reinforce-
ment. Indian Standards Institution

3. IS : 5525-1969 Recommendations for detailing of reinforcement in reinforced
concrete works. Indian Standards Institution

4. IS : 4326-1976 Code of practice for earthquake resistant design and construction of
buildings (f'irsi revision). Indian Standards Institution

5. IS : 432 (Part I)- 1982 specification of mild steel and medium tensile steel bars and
hard-drawn steel wire tor concrete reinforcement: Part I Mild steel and medium
tensile steel bars {third revision). Indian Standards Institution

6. SABS : 1044-1978 Code of practice for detailing of steel reinforcement. South
African Bureau of Standards, Pretoria

7. IS : 1786-1979 Specification for cold-worked steel high strength deformed bars for
concrete reinforcement {second revision). Indian Standards institution

8. IS : 1566-1982 Specification for hard-drawn steel wire fabric for concrete reinforce-
ment {second revision). Indian Standards Institution

9. IS : 962-1969 Code of practice for architectural and building drawings {first revision),
Indian Standards Institution

10. CEB Application Manual on Concrete Reinforcement Technology (Bulletin D' Infor-
mation N°140), December 1981 /September 1982— prepared by Euro International
Committee for Concrete. Published by Georgi Publishing Company— CH 1813 Saint-
Saphorin, Switzerland.

11. John A. Barker. Reinforced Concrete Deld'iVing {second edition). Oxford University
Press, London

12. IS : 1139-1966 Specification for hot-rolled mild steel, medium tensile steel and high
yield strength steel deformed bars for concrete reinforcement {revised). Indian
Standards Institution

13. ISO 3766-1 977(E) Building and civil engineering drawings— Symbols for concrete
reinforcement. International Organization for Standardization (ISO).

14. ISO 4066-1 977(E) Building and civil engineering drawings — Bar scheduling.Inter-
national Organization for Standardization.

15. ACI Detailing Manual— 1980 (Publication Sp-66). American Concrete Institute,
Detroit.

16. Reinforced Concrete Detailing Manual- 1975. Concrete Institute of Australia

232 HANDBOOK ON CONCRETE REINFORCEMENT AND DETAILING

ACKNOWLEDGEMENTS

The following clauses and figures in this publication are reproduced by permission from the

publications indicated against them

Clauses --^.9 to 8.10.2, 10.4 and 11.6
Figures - 8.29 to 8.36;

10.6, 11.19,
1.23, 11.25 and 11.26

11.21

Clauses

Figures

13.1 to 13.3.1, 13.4 to 13.4.5,

4.4.3.1, 4.4.3.2

4.8 to 4.15, 13.5 to 13.18

Reinforced Concrete Detailing (second edition),
by John A. Barker. Published by Oxford
University Press, London, 1981.

CEB Application Manual on Concrete Rein-
forcement Technology (Bulletin D'
Information N°140)

December 1981 /September 1982— prepared by
Euro Internationa! Committee for Concrete,
Paris. Published by Georgi Publishing
Company— CH 1813 Saint Saphorin,
Switzerland.

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

-L L.

R3R;30TH.I>flERN*LW*LL FPU tJOTK EXTEBIW. WALL FOR tlS TH. IWTEP»W,WLlI'

TYR DETAIL OF FOL)Mn*TinN F^ R HRirK Will

''niri

rf^ —

1_ —

— ft
"7

-t^

7^-

i IN

FOOTIMt, SCHeOULE

TTP DETAIL O F^ COLLIN S

FOOIIMG
MARK

OIMEHSIONS IN

BFI SHMZIHG IN M M.

REMARKS

nc 1 „B

10 M

1050

ISO

*10®1«

*10®U0

1Z0O

1200

JOO

jinoca 120

«MO@>M

USO

b.^

3 00

^10® 100 |«io@no

OCNERAL NOffS:.
Au OMENSwie ARC IN » I. UNLESS HOTCo orHtmnc.

tKABC OF CONOKTI MX SHALL K H IS COHFOMMN TO
IS: ISt-lt 7t.

HaNPIMCCHCNT SHALL ■( HWH STROWTH OCFOMMEO gAMS
OF SRAOE F<: 41S COMFORHIfW TO tS:U*l-tl«.

FOUNDAIIOM PLAN

FOUNCATION OETAfL OF
ISOLATED FOOTING.

235

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

isft:

^ W
m

TYP OETAiLS OF COLUMN

SCHEDULE OF COLUMN REINFORCEMENT

hmo UP 10 rmsT floos

ynSUP.TO JNO FLOOR.

:«!2 Aeovf 2ND FLOOR

<jf 15 UP TO FIRST FLOOR

M'.l UP TO FIRST FLOOR

3# 20 UP TO FIRST FLOOR

•=

3» 20 UP 10 RR5T FLODR

3# 16 ABOVE FIRST FLOOR

2# 23 11= TO FIRST FLOOR

2* -i -Ove FIRST FLOOR

UOi^OO SPO ilM,

i::

if"

_±aiT or* uvtL

ft'%

UNDER REAME D COMPACTION PILE

Ifoh CIA)

SPLICING AND PEDESTAL DETAIL

IGENERAL NOTES:

1 MX OMCKSDNS ARE IN in m UNIESS NOTED OTHEmiBE.
l\ MADE OF CONCRETE H« SHALL BE M 20 FDR PUS AND

HS^R OTHER CONFORMING TO IS: iSI-ll7«.
Ij REWFOICEMEKT SHALL BE MGH STRENOIH DCFORI^BM

OF ORADE F«: ill CONFORMING TO IS: 17II-IIM.

C0VB1 TO REINFORtZMElff SMALL BE AS ALLOWS: -

fILES — 50 mm

COLUMN IQnini

C BOTTOM SO m HI
TOP AND SIOES iO mm
«RAOE 8EAH'7Smm.
SJ LAP LENGTH INREMORCMG BARS SHALL CONFORM
TO CLAUSE 2S U4 OF IS:i&t-1f7l.

FOUNDATION PLAN

LAYOUT T BUILDING SHALL BE DONE AS PFR AftCHT DRWG

FOUNDATION DETAILS PILES,
PILE CAP AlW GRADE BEAM

SHEET -2

237

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T}-1

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-19

As in the Original Standard, this Page is Intentionally Left Blank

SP :34(S&T)-1987

(!>-

(5>-

®-

(jy

(HKf

i "^

^D C3

& n

J 3J O0 liw ;

a D

d) ® (?)

PLAN OF BLOCK -C

THE HOOK IN CLOSED TIES

2TI

THE HOOK IN OPEN TES

T^BLE OF COLUMN ftEINFORCEMENT FOR BLOCK -C

Ht.IZ.Ht.IS

IROI FQUN-
0»TION to
JND- FLOOR

REIN FOBCgMt*

"1 SeCIIONS

I. --a It
■■« u

S-Jtc 33

' t (S 100 Jr

■ » (a 100 *

XT a ^ 130 ff

it I a 100

2S 1 * 8 (5 10T

1300 1 QD

30a>iOO , DO

■ ( ® 100 * » gi

SHAPE Of '

B^no^cj

□>n^a

n^D^a

□*n^^

n^D^a

I-JfJS

n^n^nS

nmhS

□^D^D^S

.n^a

n^D^

n^n^a

□-□^

n-c3*^=^

i D-0

^JL

KEY PLAN

^ [= I FLOOP ,BE>M _

□

IMTtBMEOIATE Float -

flYP TERMINATPOW OF

Ua*ns'iN CASE LOWER
COLyMN SECTION
<H*VE MOHE WJPWeft
iOF lAltS THAN
lUPPES COLUM* —
iSECTPON

tOP Of PILE CAP

TIE SPACING OETAIL ""si-'^^ja^

COLUMN SPLICING OE TAILS

GENERAL NOTES

COVER TO RSINFOflCEMENT SHALL BE 40 ""<

NOT MORE THAN HALF THE COLUMN BARS SHALL BE LAPPEO
SECTION.
frjcONF(NH4G STIBRUPS in 8EAH-C0LUMH JEHCTION SHALL BE

PORtlON Af THE SPACING INOICA^EO HOWEVER If BEAMS ARE
CONNECTED OK ALL THE FOUR DIRECTIONS Of COLUMNS THE SPACING

SHOULD at ooueLEo- w case of difft:lilty in phovidiho closed

STIRRUPS, U-TTPE STIRRUPS MAT BE PROVIDED'

LAP LENQTH small be SO TIMES THE DtAMflER OF SAR

DETAILS OF COLUMNS
REINFORCEMENT

COBPORATtHO OUCTILITT
FOB SEISMIC DESION

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-I987

DETAIL -A

DETAIL- B

DETAIL -C

^-CONSTRUCTION XJINT

TYPICAL SPLICING DETAIL FOR
ttlLUMN fteiNWRCg^gNT AT

Tci

^ -^PEDESTAL

INTERMEDIATE LEVELS
9

^PCC.

DETAIL OF ANCHORAGE OF REINF
AT BASE OF COLUMN

^ I s HZ

[TYP)^ | 75|7S i 75 | T5|

AT THIS
LEVEL

STIRRUP

SCHEDULE

MAX.DIAOFplAOF
MAIN RONSSTIRRUP
IN COL.

SPACING OF STISHLIP

NORMAL ZDNEJLAPPING ZONE

iOa.36

#■10

® no

@ 12S

AaOTtCRS

ff 8

® 2SQ

@ I2S

FDR 13 5^ HOOK FOR 160° HOOK

TYP DETAIL OF HOOKS

ALL DIMENSIONS ARE IN mm UNLESS NOTED OTHEfWISE.
fieiNFORCEMENT SHALL BE HIGH STRENGTH DEFORMED
BARS OF GRACE F« : 4,15 CONFORMING TO 13:1786-1965.
GRADE OF CONCRETE MIX SHALL BE M 20 CONFORMING
TO is: 456 1978

CLEAR COVER TO REINFORCEMENT SHALL 9E 40m.m
M CASE OF COLUMN.

(COLUMN REINFORCEMENT SCHEDULE ANO GRADE OF
CONCRETE COVERED IN A SEPARATE DRAWING MOT
INCLUDED.)

ALL SaaNOARY TIES MAHKEQ SI SHALL BE ai<§i 250

DEmiL OF REINF AT
CHANGE OF COL. SEC

DETAILS OF COLUMNS

SHEET 6

As in the Original Standard, this Page is Intentionally Left Blank

SP:34{S&T)-19«

j" ! L..„ ffl> no ., a 230 I aiM J I ' > no . ; ja wo .

.700 ;

T
; 2000

-(-'^ -L-

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10 iLCG- 13 ^:

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114 jjrn 4-

aCTAlL OF CAHT 9EAM FSOH

cecAM sfcnoH ^ooxico i

GENERAL NOTES

ALL DIKSNSIOHS *S6 IN m m UNLESS WITED 0TMEBWI5E.

SHADE OF CONCRETE MIX SHALL 9E MIS CONFORMINi; TO

ISr(St-l«r<

REIMFOHCEHENT SMALL BE M<SH 5TIIENGTM QEFOnMED

BARS OF CRAOE ft.l.l'. CONTORHIMQ TO IS:|7<i-l9>S

COVER TO ReiTORCEHEMT SHALL SE 2SiTim«n THE

DIAMETER OF THE BAR WHICHEVER IS SflEAIER

DETAILS OF BEAMS
( iNConfOAAiAiNa DuciiLUT pw

FOR SEISMIC OESIOH I

As in the Original Standard, this Page is Intentionally Left Blank

-^.■. 1 i

I I

IMC V '«" I

-Si^ ^

|i Irrnl lU 5

hflTlT"' "r^*^":, jl

BEAM ALONS GRIP 1 4. 13

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REINFORCEMENT SCHEDULE
OF SEAMS

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SP : 34(S&T>-19>

I U ! "

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TOP
BOTTOM

GENERAL MOTES

ALL DIHENSIOWS ARC 1« mm UHIESS
NOTED OTVIiRWISE.

(iRADE OF CONCRETE WK SHALL SE t* IS
CONFORMING TO IS:1SS-197I.
REINFOnCEMENT SHALL BE HIGH STIKNGtH
DEFWHED BASS OF OflAOE F» ^ * I S CO«R»»«|-
^NO TO (S;178«.1S«,

DETAILS OF SLAB

( USWO SCNT-UP BAHt i

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-I987

As in the Original Standard, this Page is Intentionally Left Blank

SP:34(S&TH987

As in the Original Standard, this Page is Intentionally Left Blank

SP : J4(S&T)-1987

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RIB ^ HI6 JUNCTION

BIB a. SLAB JIXTION

»IB t BEAM JUCTION

DETAILS OF BEAMS AND

RIBS

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34<S&T>-I987

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34{S&T)-I987

267

As in the Original Standard, this Page is Intentionally Left Blank

SP :34(S&TH987

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

r r

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Lf L-{fctO AL1-|

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VIEW C-C

REINFORCEMENT OETAICS OF BASE SLAB

• BARS ARE IN THE SAME PLANE. BUT TWy ARE SHOWN TO BE IN DIFFERENT PLANES
FOR THE PURPOSE Of CLARITY

G^ERAt NOT^.

aucC Of CONCRETE MK SHALL IC M II OWRNI
n tS «M-IIM-

REWnRCCMENT lAIIS SHALL IE HMH 3TRCMTN
OCratMCD BARS OF OMOE T*:/,i% COWCMMRM
Tt is: !»!§-««•

OETAIUS OF UNDERGROUND
WATER TANK-OPEN AT TOP

SHEET 19

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T).1987

As in the Original Standard, this Page is Intentionally Left Blank

SP :34(S&T)-I987

^^^^I^l'^^i!^^^'''^ COILS AROUHPCnUF.;

TENSION r-^*^l>

;tt«.»oijiL

[GENflAt. NOTES

(I AU. OMCHUMI M( •. «„UI«« HtnCO u,™™
I MMX Of OIHOICIE MIX Smui ■• u It OMFORMM
I TO l$:iSI-itM-

ra IS iiiimmit an *wi mmwidj

C0»O 10 MCIMr<»CCHfMf SHALL t( 10 „■

JOINT-B

DETAILS OF BC.C. PftCCAST
TRUSS OF 5P*N 18 M

As in the Original Standard, this Page is Intentionally Left Blank

SP : 34(S&T)-1987

f^'

UlMflO

1/& PLAN SHOWING 2nd A 3rd LAYER
OF RADIAL REINFORCEMEH

Wt. PLAN SHOWING CIRCUMFERENTtAL

PLAN SHOWING BOTTOM RE1NFORCEMO<T

DETAILS OF FOUNDATION
RAFT FOR CHIMNEY

SHEET ii.

277

AMENDMENT NO. 1 MARCH 1989
TO

SP : 34 ( S & T ) . 1987 HANDBOOK ON CONCRETE REINFORCEMENT

AND DETAILING

( Page 30, datise 4.3.1.2 ) — Add the following matter at the end of the clause:

If for one bar size, straight anchorage length, L^t will develop the tensile design yield stress in
tension, then by bending a standard hook or bend at the end. a length { L^* — L© ) will develop the
design yield stress also. This aspect is illustrated in the figure given below, where Lax is the develop-
ment length in tension and L^ is the anchorage value of hook/bend. In some cases the length
( Ldt — ^e ) will have a negative value, io which case it shall be assumed that the hook/bend alone
provides an adequate development length.

Ldt

Ldf-i-fi

■^

Ldt

(Lh,-L

i'j

When hooks/bends do not Cv>nform to standard bends/hooks given in Table 4.1, anchorage value
of hook/ bend shall be neglected and the total development length provided ( measured along bend/
hook ) shall be equal to the required development length { I^t ).

A few examples concerning development length in tension' are illustrated in the following figures:

-CRITCAL SECTIOM

"^ 2C I " -^ ! —

■

IISC

Available space for straight bar =

1 150 - 25 -= 1 125
Ztit required ( for # 20 ) = 1 128
.-. Straight # 20 wilt et

#26^

UDO

Available space for straight bar =

1 400 - 25 = 1 375

/^dt required ( for 4^= 28 ) = 1 580

.Straight # 28 will not fit

( iLat - Z^e ) = 1 580 - 224 - I 356
.'. # 28 Bar with standard bend will fit

Gr I

r--^lO

560

40 COVER

560

^^n

UQ COVER

465

I 350 I 1^0 C OVER

^12

^jiT-

677

Available space for straight bar » 560
Zdt required ( for # 10 ) » 564
/. Straight bar # 10 will lit

Available space for straight bar = 560
idt required ( for # 12 ) = 677
Straight bar wilt not fit
( I^t - Le ) = ( 677 - 192 ) = 485
4^ 12 with standard hook wilt easily fit

Available space for straight bar = 350

Zdt required ( for 4^ 12 ) = 677

( Ut - le) ^ ( 677 - 192 ) = 485

Straight bar with or without standard hook/bend
will not be suitable

Provide # 12 bar with full embedded length =
677 and also check for bearing stress at the end

< Page 41, clause 4.5.2 ) — Add the foUowiog at the end of the clause;
^However this should be subject to the following conditions:

a) Where the bar does not .extend beyond a point four bar-diameters past the end of the bend; and

b) Where the bar is assumed not to be stressed beyond a point four bar-diameters past the end
cf the bend at the ultimate design stress, that is, where the length of the bar extends beyond
4 ^ from end of the bend, it is not considered for development length.*

< Page 46, Fig. 418) — Delete •STANDARD' in the legends.

< Page 47, Fig. 4.19 ) — Delete 'STANDARD* in the legends.

< Page 70, Fig. 6.1, Note 1 ) — Delete 'standard'.
(Page 71, Fjg, 6.2, Note) — Delete 'standard'.

( Page 79, Fig. 6.11, SECTION AA ) — Delete 'STANDARD' in the legend.

(Pfl^c8l,fyg. 6.13) — Substitute 'LAP SPLICES AT MID SPAN. ri= REQUIRED' for 'LAP SPLICES
ATMlDSPAWi IF REQUIRED" and the same should be referred to top steel instead of bottom steel as
shown by the arrow line.

( Page 129, Fig, 9.7A ) - Delete 'STANDARD* in the legend.

( Fages 181 to 185, Fig, 11.29 to 11.33 ) — Change Fig. 11.29 to Fig, 11.32; Fig. 11.30 to Fig. 11.29;
Fig. 11.31 to Fig. 11.30; and Fig. 11.32 to Fig. 11.31.

( Page 181, clause 11.9, line 5 ) — Substitute « Fig. 1 1.34 'for • Fig. 11.32 '

( Page 185 ) — Add the following Fig. 11.34 below Fig. 11.33:

VERTICAL FORCE

APPLIED
MOMENT

SHEARING EFFECT AT
JOINTS WlTH.SLAQ

\Zl

BANDS OF

HIGH COMPRESSION

CENTRAL
SECTION ACTING

AS DIAPHRAGM

FIX EC-
EDGE

COMPRESStON^
fiAND

(MAIN REINT.}

1 1 .34A Fo rces i n Shear Wal I

(NOMINAL REINT.)

STRAIGHT BARS

COMPRESSION
BANp

(MAIN REINTJ
nLINKS

-FREE
EDGE

U-BARS

11.34B Cross Section Showing Typical Details
Fig. 11.34 Shear Wall

( Page 211, Table C-1, SI No, 3 ) — Substitute '5-0' for '3-0' in col 3.

(Page 449, Sheet 8 )— Substitute '(SEB SHEET 10 for reinforcement SCHEDULE)' for '(See
SHEET 9 FOR REINFORCEMENT SCHEDULE )' in the title block.

( Page 253, Sheet 10 ) — Substitute •( REFER SHEET 8 FOR ARRANGEMENT OF REINFORCEMENT )' for
'(REFER SHEET 9 FOR ARRANGEMENT OF REINFORCEMENT )'.

( SCIP )

Printed at Nutan P ri nters NEW DELHI

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